The USA still prohibits guilt by association.
If this was a turf summit to divide up illegal activity then the police should have just had a warrant, recorded this, and made arrests later when this fiasco could have been avoided.
I'm sure you are aware of anti-gang laws.
But anyway, it's not particularly surprising to hear that someone who was having lunch with criminal gang members got shot or arrested, for whatever reason. It's about as surprising as rain on a monday.