Well, I certainly don't disagree that people shouldn't be vandalizing this building with posters, I don't see anything that would suggest violence.

Keep in mind, I'm not arguing that they should be putting up these posters (clearly they shouldn't be), just that there's a big difference between non-violent defacing of property and taking up arms in some kind of street-level terrorist cell opertation like other comments here are suggesting.

These posters seem more to be a play on signs like "Swim at own risk; No lifeguard on duty". For signs at the pool, they point out that there is a risk of drowning if you go swimming on your own with no supervision, not that someone is going to come up and stab you in the stomach and shoot your kid for swimming. These posters on the building are like that. You can gentrify, but at the risk of damaging the quality of life for the current inhabitants of the city.

I actually can't really see any other way to interpret its meaning. Nothing about this says "we're going to cause violence" to me.