Exactly. Just because we disagree on what the total "package" of human rights ought to consist of doesn't mean that we need to throw out the concept. It's likely that we have commonalities in terms of what specific things we value as human rights. In this case, the rest of the western world finds Russia's concept in drastic and serious contrast to their own shared one.
When it comes to which concept is morally right, I think we can point to things like the fact that Russia's law is doubtful to maximize the well-being of everybody involved (particularly the gay people of Russia). Alternatively, we could say that Russia is trampling its citizens' autonomy and not respecting their statuses as rational people, fit to make choices about their own lives. and if we really, really wanted to, we could say that Russia's lawmakers are not being virtuous people in enacting this law, and probably also that anybody enforcing this law is not being a virtuous person either.
So we've covered all the standard moral bases. It would be pretty easy to show that Russia is acting in an immoral way. If Russia's conception of human rights is an immoral one (based on the previous), then we should be able to say:
1. some conceptions of human rights are more morally desirable than others (read: better)
2. All other moral conceptions of human rights are more desirable than Russia's.
and while I'm in the mood, arguments like yours (you seem to indicate that no brand of human rights is superior to another) really don't work in the face of the law of non-contradiction. If we've got two statements like: murder is wrong and murder is NOT wrong, they cannot both be true simultaneously. You can't have M & ~M, as it's obviously false. The point of that example is that although we perhaps cannot know which is the case, it would seem that there is a fact about the matter. If there are facts of the matter about all of those sorts of statements, then they can't possibly all be equally valid like you think they are. There are better ones and worse ones, but, again, we just don't know which are which.