Ultimately, though, the idea here is basically to capture that satisfyingly vindictive feeling of smashing an opponent's carefully built fortress by pulling down one flagstone- that sort of trolling/griefing where you just completely ruin something that took a long time to reach with minimal effort, and make it into a competitive strategy game where the entire game is basically the players griefing each others' infrastructures one after the other. If there's a simpler way to reach that sort of gameplay, I'm all ears.
All you've done is ensure no players will ever defeat the others because it's so easy to sabotage their infrastructure, thus leading to all players unable to progress beyond a certian point .. and you've really only replaced "Tech tree rushing" with "Attack the other guy's infrastructure". It's also rather obvious what parts of infrastructure to attack in order to cripple them.
While the idea isn't completely bad, the way you have it planned out is too effective for too little effort. A better idea would be to give more incentives for military and economic attacks on other players, or restrict it to attacking certian parts of infrastructure that slows down tech development, but doesn't cripple it and cause the player's entire civilization to collapse overnight.