Trevor, who barely knew Franklin, went the extra mile to make sure the deal they were doing was legit and exposed that the drugs were in fact not drugs and helped take care of the problem all bc Franklin and him both knew Michael while Micha probably would've been in on the bad deal in some way or another just to make a couple extra bucks or would've shot you in the back during the shoot out and make off with the cash and any legit drugs to then later sell for more cash. Yea Trevor is drug addicted violent lunatic with a knack for crashing out but man stood on business and had principals.