Yeah, i was very confused by that, especially after they invited them to post publicly/privately. They love controlling the public communications when it comes to researchers. I remember ryrona, a guy who found VPN leaks, being censored for no reason whatsoever in their public GitHub issue tracker.
I think it was good that this exchange was later deleted, but it would have been better if the interaction had not gone in that direction in the first place. He appears to do strong technical work, and I do not want to diminish that. At the same time, some of his communication can come across as unnecessarily dismissive, confrontational, or unprofessional. That makes already difficult technical discussions harder than they need to be.