Falls into the bucket of "specialists can have weird hobbies" element though - i.e. the background to do this is basically "has access to lead oxide, copper and red phosphorous" and "a kiln" - particularly if you dispense with trying to do the vacuum synthesis as that account claimed too (also a point in favor: having random access to dangerous chemicals is sort of something I'd expect out of states with less enforcement of drug synthesis laws).

The mechanism is plausible - if the reaction actually proceeds by driving off the sulfate and substituting in the copper at high temperature, it's entirely possible the vacuum synthesis of the authors is unnecessary (I have in fact had personal experience with trying to replicate a paper where it turned out that a pretty important step was acting as an oxygen-diffusion rate-limiter, and this just...wasn't identified at all by the papers authors).