That's effectively impossible as a part of the nature of the fediverse. You could try banning alts on site but it's really not that hard to have a dozen alts waiting across host of instances.
They usually don't. Like with Newbuild, they change who they refer to themselves in 3rd person. But an account saying they are friends with Drag, speaking exactly like Drag, but referring to themselves as, in this case, Bot... Almost zero effort to conceal the alt as an alt.
You'd have to distinguish drag from others using drag neopronouns for fun and or profit. Drag thinks this would be fun for a while, if only to prove drags point dragself.
Did they ever use dragself? I bet they did. We'll never know now.