'break', like crack the body? It takes some force to break a guitar in the first place. I can't picture a simple blocked floating bridge providing that much force. But I could be wrong.
No, unless the guitar takes a hit so bad as to crack the body. Even if you try to use the bar while it is blocked, the worst that can happen is the bar snaps off in the block.
I imagine under enough stress a cheap trem block could crack, one of the skinny potmetal ones.
But i can't see it breaking the wood body. Really soft wood like paulownia might deform a bit.
In order to apply enough force to the blocked bridge to physically crack/break/damage the body of the guitar via the trem cavity, you would have to be intentionally trying to break the guitar. Otherwise, no.
Nope. A blocked trem is pretty much the same as a fixed bridge. It would take the same damage to break a fixed bridge guitar as one with a blocked trem.