I don't think him having crippling anxiety would stop him from being manipulative, but it does make it a lot harder for people to be critical of him because he keeps bringing it up, even though just because you have anxiety or depression doesn't mean that you can avoid criticism. Really for Gary to block people, he should either have an open account for his followers to see his persona and have someone deal with that instead of himself so they can deal with the comments that could upset him, and then a private one for his friends and family.
I do agree that Adam should change his channel if all of his content is going to have Gary in it now. Though I did like his vlogs when he had a variety of other people in it, Sam is a good example, the two guy's from that cruise ship vlog a few years back, the one with the woman from last year on an European Disney cruise, it was just a variety of people for Adam to interact with and they brought something different to the vlogs.
Now it's just the Gary and Adam show, it's a bit... beige really.