I tend to agree. As a neighborhood watch member, he should have observed, not escalated. An equally poor decision on the part of the youth further escalated the situation, it would seem.
If it comes out in any way that Zimmerman initiated the assault, then I would think that he's in a world of legal trouble. But I haven't seen any evidence to support that theory as yet.
You have the most reasoned replies I’ve seen regarding this issue. I agree with your assessment of the entire situation.