Well if the SYG works the way I got the impression, this would count as a Stand your ground scenario. No seriously, if all you need is to "feel that your life is in danger" then all he has to do is say that he was scared of those teenagers.
Does it matter if he put himself in that situation on purpose? It didn't for Zimmerman.
Does it matter if the "gun" he saw was a stick or just a finger? As long as he THOUGHT he saw a gun he was still afraid.
I mean if the law says that all you need for SYG is to be in fear of your life, then all he needs is his own word that he felt afraid of those teenagers that he specifically went to pester and he therefore had the right to shoot them.
So unless I'm mistaken about the law (and lets face it, both the people for and against SYG love to misrepresent it to suit their own agenda) this is a standard SYG situation and an good example of why that law is so horrible.
As a side note, apparently 22 states in USA have some variation of it and 46 in total have either SYG or Castle doctrine. So I guess I won't be going to USA anytime soon.