Yes they kind of are. I’m not sure how many Firefox users there are in Russia but some how I think there enough that it would be yet another bad look for the authoritarian government.
If Mozilla gets blocked, people would just install some other browser (probably, something from Russia). I do not see how this helps anyone but the government itself. And departure of hundreds (if not thousands) of western companies did nothing to the Russian government, some problems with a browser with almost non-existent userbase would have the same effect. It should be quite clear by now that such tactic simply does not work.