Maybe he doesn't want to be associated with bodybuilders from that era that made porn for a living.
A guy who won the Arnold Classic three times fucked a grapefruit and got blown under towels -

.
Drasin was a minor star in an obscure porno film.
My guess is Drasin's channel was too small for Arnold to come out for, and he didn't want him making money off his image. Also Drasin was tight with Robby Robinson, and Robinson did a press tour trying to hurt Arnold's credibility during one of his gubernatorial runs.
There could be an unspoken grudge there.