-Where does it say the 'gun' (proper legal term is firearm BTW) has to be holstered?
It doesn't legally have to be.
-There are holsters that fit in the waist band just like 2Pac is carrying.
-It is not illegal to carry into a police station. (unless properly posted, but unlikely)
Posting doesn't matter, it's not illegal.
"-It doesn't matter whether you're dressed like a banker or a homeless person, carrying your piece on the outside is a big sign that says "I'm a big tough guy, you better not mess with me because I'm a billy bad@$$", but seasoned criminals see it as "I think I'm a big tough guy, but really I'm a newb and you can take this gun from me easily"
This is just silly. More importantly, it can't be substantiated in anyway.
I think it's easy to convince someone of the legality of OC. This is pretty black and white. It's much more difficult to convince someone that it's a good idea to OC. If someone would rather CC, I could care less. You don't need to tell someone how to carry (not that you were) and they don't need to do the same. If someone thinks it's idiotic to OC, all you can do is explain your point of view. If they don't accept it, it's not your problem.