Adams has recently come out as a Trump supporter. Maybe that's it? He's still a strange choice of target, since he's not (as far as I know) one of the crazies screaming about "cucks" or Benghazi or whatever.

Personally I've found his blog to be pretty helpful for understanding the Trump phenomenon better. http://blog.dilbert.com/

Wasn't he an office drone before drawing Dilbert?

He was. His experience being a drone is where he drew his inspiration for Dilbert from.