If something is illegal in a country, then it should be blocked for that country. It's not Mozillas decision what a government allows and not. It would be different problem if the extensions were blocked worldwide, but its not. It's only blocked where its illegal.
But, that above statement by me is about laws. I'm not so sure how to feel about government requests, if its not even against the law. Is there any law in Russia that forbids those extensions? If not, then I'm with you and this is bad. But if there are laws in place and the government asks to block them because of the law, then it's totally fine.