Interesting that they differentiated between sex and gender here, and in the right way too.
Interesting that you appear to believe that international standards for medicine, medical science, and biology *don’t* make a clear distinction between sex and gender. Or that trans people themselves don’t.
it's Russia coming up with what should honestly be the world standard for dealing with transgenderism.
Also interesting that because sex ≠ gender, you automatically jump to the conclusion that only sex matters. Or alternately, even if gender matters to the individual, then society has an overriding interest in enforcing “only sex matters” above individual needs, interests, and/or concerns. And that either way, international organizations and/or communities have an overriding interest in forcing most/all societies into accepting such standards.
I will also point out that in the case of Russia specifically, Putin doesn’t believe that Gay/Lesbian/Bi people are real, there are only straights who engage in deviant behavior, but that Trans people are real but too dysfunctional to be proper Russian citizens. The laws of Russia reflect his personal beliefs (previously, trans people couldn’t legally have driver’s licenses, because they were “clearly” too dysfunctional to be able to drive), and the personal beliefs and/or whims of a single dictatorial leader are not an actual justification for anything.
There's no way to change a person's sex
That depends on exactly on how you’re defining “sex”. There some few reasonably objective ways, but each of them fails to 100% sort people into a strict binary, there are always people who don’t quite fit. The possible exception is strict genotyping, but most people don’t actually know their genotype and this has always been completely irrelevant from a social/legal perspective. And by some definitions, it is possible to at least change someone into a form of intersex which externally resembles that of the opposite sex, which is a genuine change.
Also unspoken, but often implied, is the assumption that either this will never be possible in a way that they would acknowledge that their sex was genuinely changed, or else once it becomes possible society will have an overriding interest in banning that as well.
people with DSDs being the exception.
Even if we were take everything else as valid, and that there’s also a similar overriding interest in forcing intersex people to conform to a sex binary, it’s of further note that in the vast majority of cases, they don’t bother to genotype children or confirm their internal anatomy and instead make a “best guess” based purely on external anatomy. In other words, they’re not using any reasonably objective concept of sex when determining which binary sex the child should conform to.