Any weapons charges were dropped before they went in for deliberation, so it is moot.
Would you go into something like that as a 17 year old? He wasn't "stuck out there"! He went there intentionally, with some warped idea that he was needed.
What part of "I know they're rioting, looting, burning & being violent and I want to go there" sounds like a good idea?
Rosenberg had already attempted suicide- he may have approached because he still wanted to die, but we won't know that, for sure. Huber had a skateboard and apparently never heard the saying "Don't take a knife to a gunfight". WTF did he expect to accomplish with that?
The store owner and Rittenhouse situations aren't similar, in any way. The 70 year old man had something to protect, Rittenhouse only thought he should be there to protect- big difference. A 17 year old couldn't be hired to act as an armed guard.