Write him & ask. Only he knows for sure. It would be interesting to hear his response though, if indeed he bothered to respond. My guess is he was significantly shaken in some manner or fashion, to do a 180 with regards to Trump. When your livelihood or life itself, is threatened, and the threat is perceived to be a credible one, it would probably change the tune of most people.
Your guess sounds right. It probably has to do with blackmail, most likely including photographs.
Drudge is a homosexual and many (most?) homosexuals have engaged in unspeakable acts of perversity at some point in their life. Not that "normal" homosexuality isn't perverse enough …
This is why homosexuals are denied security clearances—threat of blackmail.