I'm a little late to this party, but as a plunderer, I'm going to critique this strategy a bit.
Disconnecting roads is a pretty poor strategy for deterring a plunderer. It might deprive the plunderer, but it WILL deprive you. Disconnecting the whole city is just ridiculous. However, a more limited disconnect isn't too bad with the new building sets. I arranged my city with that in mind just in case:
If I get into a hood where I'm facing someone who's a harcore plunderer, I can disconnect two little road tiles and cut off my statues and Zen Zone while leaving everything else hooked up. This is pretty much a last resort situation though, where I'm likely to lose collections from those buildings no matter what. The set buildings have that whole disadvantage of not being able to be motivated, but a full set of them can give some decent bonuses to the city.
In any case, your setup as shown in the first post isn't that great, since you're cutting off some SoKs. There's no need to cut them off from plunderers; their main use is to generate FP, and they don't generate them unless motivated. Plunderers won't hit a SoK that's ready to collect if unmotivated since they only make coins then, and we really don't need coin.
That parallel stretch of road where you have your houses isn't too bad, that's an effective way of plotting out your city. That loop going around the military buildings just wastes space though. You should get rid of the SoI too, it's a space hog for what little it produces, if you need BPs, aid everyone you can regularly, and join a decent guild that swaps FPs on GBs. You should get those Farms upgraded to Breweries or at least Cooperages too.
1. Build a decent army and swap the defense regularly. This will deal damage to their units and make it more difficult for them to fight you. It will also lull them into a sense of false security, stroking their ego as they're led to believe you're actively and unsuccessfully trying to counter their flawless attack strategy. Then, if they win, they will excitedly try to plunder you only to see the disconnect icon hovering over your best buildings. Check out
https://forum.us.forgeofempires.com/index.php?threads/general-defensive-military-guide.8654/ to find the best defensive combinations for your current age, if you're so inclined.
That occasionally helps. Swapping your army won't stop that guy who's got a built up military machine unless you're pushing a very high defense. Swapping hasn't blocked me all that much. For your particular city though, you should look into doing the bonus questline for LMA and get some CA troops to bolster your defense. Finish the EMA one if you haven't for that Monastery too.
2. Place the moved roads somewhere highly visible, so they can see what horror you've wrought.
I've seen plenty of cities like that in 7 months in LMA, and I have to honestly say I'd classify them as comedies instead. That's pretty blunt, but a city like that isn't going to scare me at all.
3. Build cultural buildings and landscaping decorations to maximize your citizens' enthusiasm and compensate for any deficit that is created by unplugging your automatic-production buildings.
Um, no. Decorations usually have very little effect on enthusiasm unless they're special ones from events. Even the Faces of the Ancients and Gates of the Sun God from the GE that everyone bitches about aren't too bad for some happiness (really the problems with them is that we get more than will ever, ever be useful). They also have another serious flaw, they take away aid from your houses and production buildings. Culture buildings are also aid vampires AND they take up valuable road space, but they generally have better happiness per tile. You said you just built a Hagia, so that will provide you with some happiness for a while, enough that you won't need to rely too much on culturals or decos.
4. Conversely, have no army whatsoever, your defense being two measly spearfighters. Too good to be true? Absolutely!
Two measly Spearfighters does nothing but put you at the top of my plunder target list.
5. Use flowers, bushes, and other one-squared pleasantries to craft a lovely message such as "Go Away," provided you have enough free space, of course.
Unless you're doing this with Watchfires and Tribal Flames, no. Remember what I said about decos taking up aid while providing pitiful happiness? The only use for decorations is if you have so many guild mates and friends that there's not enough things for everyone to motivate in a day's time, it at least gives them a chance to earn a BP. Just don't use Stone Age decos.
6. If you're going to be AFK for an extended period of time, set your supplies and goods buildings to a 24-hour production or don't produce at all. Buildings can't be plundered while they're actively producing something.
That's one of the most solid pieces of advice you've given. Even then, if you can't reliably collect on time, even on a 24-hour schedule, I'd recommend avoiding goods buildings altogether, and probably the set pieces as well. Go for the goods producing GBs, you're got the Babel and LoA, next try to get St. Mark's and the FoD. Also, go for special buildings like the Oasis or Tribal Square that produce goods when motivated. It's a little slower when you're not making your own goods from goods buildings, but at least the goods won't get plundered. Supplies at least can be motivated and protected, and really what a player needs to do is build up a good social network. Join an active guild that matches your playstyle, and recruit reliable friends that will regularly aid you.