It is right not to let him play with his brothers camera unless his brother was asked if he could,he should not have torn up the Bush,did you ask why he did that, also he could be jealous of his Brother, I assume the Brother is older to have a Camera, perhaps some extra attention for him from his Dad some sports or Ball Games to make him feel special.Actually the Punishmenst seemed Fair to me and you handled it well/
I kind of think you might be overreacting a bit.
Was this some shrub out in the yard that no one cares about - just something in a line of plants that get watered, but aren't special? (If it was a very special one, say like a very favorite rose bush, that's a different thing).
What you want to do is make him feel remorse from inside, not defensive and more angry. I think expressing sorrow about the bush ("Oh no, look what you've done, I really liked that plant") and then taking him to Home Depot to pick out another plant (one of his choosing) and making him pay a small amount for itl, maybe 2 dollars, would have a much stronger affect. And make him dig the other one up, and plant this one correctly and water it in. If you do this in kind of a subdued way, not with loud anger but kind of resolve that you will solve the problem of the missing bush, I think it would help him more to feel responsible.
And then, when can he play with his brother's camera, or how can he earn one sometime that he can play with himself?
Best wishes.
Maybe he is feeling too controlled? Or there is some kind of sibling rivalry going on?