We haven't really got deep into discussing solutions and their costs, because the mere idea of doing anything gets shot down quickly. And not-yet-presented solutions are shot for having too large cost on crates-io team, without even knowing what that is!
So here's one zero-cost solution: Change crates-io policy to say that squatting is frowned upon. Literally just a wording change in one doc.
Currently, a large portion of squatted crates is taken by well-meaning people (these "please contact me if you want this" crates). They're unlikely to be stubborn rule-breakers running a sophisticated trolling-for-profit operation. They've just grabbed a bunch of names, because that is explicitly allowed by crates-io, very easy to do, and has no downsides for the squatter. And solution to this may be as simple as politely asking them not to do that.
edit: changed that to Proposal for crates-io crate name reservation