If the ewoks were orks, it would've worked.

As someone who finds that actual scene silly but non-offensive, I could honestly go either way with how the AT-ST was taken out. Trees of that size, assuming they are quite dense and heavy, could cause a lot of damage to something like that. Of course it could be offset by how armored and reinforced they are, but I imagine the designers were more worried about the overall weight and resistance to blaster fire than physical impact protection.

The real issue is getting tiny teddy bears to lift and position them, then get the AT-ST to be EXACTLY where it needs to be and release them to simultaneously collide for maximum damage.