They weren't holding the domains hostage, though, right? You can find any other registrar willing to have you and transfer your domain from Namecheap to them (and I think Namecheap would get in trouble with ICANN if this weren't the case). So customers are mostly just inconvenienced a little.
https://www.theverge.com/2022/3/1/22956581/russia-ukraine-na...
sure, an extraordinary example, but what stops anyone from wording their ToS ever so slightly vague, that any domain is held by a shoestring