If a live tree would fall across the property line, then yes he would not be liable. If a stading dead tree that he has not removed falls, he very well could be determined to be liable.
And you appear to be the reason. It would be your negligence not his that resulted in the claim.
The guy is dumb enough to build next to a big dead pine tree, with other big pine trees right next to it, that have been there for all my life, and it's my fault? No way, no how.
There is no access for me to cut the tree without damaging fences on the other side of the tree, so if I fell the tree going away from the idiot's workshop, I'll crush my fences.
I wasn't going to cut the tree down before he built the workshop. Like someone said, these pines usually fall apart from the top down. Key word is "usually." If he wasn't smart enough to see the problem, I even told him before he started that he should take note of how close he was building to the trees. He chose to build anyway. He had plenty of real estate to move his workshop over a few feet. Not just out of range of the dead tree, but also out of range of the other trees that could die as well.
My insurance agent told me not to worry. The tree was there long before, and he will have no claim against me nor my insurance.
Same guy built his house. Laid it out under a power line. I saw it, told him. He said, no it's not. Guy is a moron... Lo and behold, they start construction and framing is going up and they realize, uh-oh, they're gonna hit the power line! So, the line had to be re-routed from a DIFFERENT ROAD resulting in 4 more power poles, hassles to other property owners, etc. all because this guy is a moron, even when the problem was pointed out to him. Literally all he had to do was move the house over about 8 feet! Who pays for these idiots? That's right, we all do.
Like I said, there needs to be an "idiot clause." If you build something right next to an obvious hazard, you shouldn't get a dime. Who knows, if his agent is the same is mine, he might not!