I think that would only be an issue if they made a big deal in public about rejecting DEI. Such a statement might also attract a bunch of obnoxious, oppositely-polarized people you don't want either. Probably the best strategy would be to not mention it at all unless forced, and then just make vague, positive statements about diversity until whoever is bothering you moves on to something else.
If you want to ignore requirements like that (or similar DEI requirements), you're going to have to forgo those kinds of customers.
That said, this is how you end with critical technology in potential adversaries' hands.
Would that work? IIRC, stock prices aren't so much about performance, just who wants to buy your stock. Decreased actual performance from "greenwashing or other ESG bullshit" might be overwhelmed by demand by ESG pots of money.
