OK, so what if he did have a CCW permit? What difference would that make?
It makes it very likely that Castile was simply in the wrong place at the wrong time, and resembled someone the police were looking for.
Castile didn't know he looked like a robbery suspect, and wasn't careful in digging out his ID. The police officer didn't know he was a CCW permit holder, and jumped to the wrong conclusion when Castile told him he had a gun.
All the rest of the "proof" is nothing more than innuendo and character assassination. Castile was not a robbery suspect -- he resembled the suspect. He wasn't a criminal with a long record -- he was a terrible driver with lots of traffic offenses.
And it beggars belief to say that a guy who has worked at a public school for over a decade (after passing the background check) and has never even been arrested for a serious offense in 15 years of adulthood is a "gang member".
Finally: as I've posted elsewhere, the commission of a violent crime by a CHL/CCW holder is so rare in the US that it's statistically zero.
Cop might have thought that this was a hostage situation.