I suppose saying this is going to be found problematic. I hope not.
Anyway. Might I posit thus……..is it remotely possible that the phrase “check your privilege” is just occasionally used in an ad-homine manner” ?

For example;

Radfem “prostitution is fundamentally a microcosm of rapeculture”

Opp “how can you say that? It gives women a choice over destitution, check your privilege”

And BINGO. There it is. That IS ad-hominem. Because even if the radfem IS opining from a position of privilege, that they’ve never had that choice to make- it’s pretty clear that even if they’re unaware that their ability to choose another means to remuneration is in itself “privilege” – does not devalue their original statement eliding prostitution with exploitation with rape.

In other words, if the system that is prostitution were entirely fine and dandy, there’d be no “privilege” to “check”.

Or as I say, “one does not have to taste aloes to know that they are bitter.”