There's about as much proof that the Kremlin killed those people as there is that Hillary Clinton killed the people who had information that could lead to her arrest.
I knew that comparison would come up, but there's really no similarity. The Clinton conspiracy theories essentially boil down to the fact that a couple of people (among thousands) tangentially involved with the Clinton investigation died from natural causes while the investigation was proceeding. Several of the conspiracy theories center around people who weren't even important in the investigation nor had any sort of information or 'dirt' against Clinton.
These people who died in Russia were murdered in broad daylight, after years of vocal antagonism against Putin and the Kremlin. Plus, are you willing to tell me that a non-governmental entity acquired Polonium and used it to poison Litvinenko? Where the hell would the mob get Polonium, and why would they use that instead of just shooting the guy?
Also I see absolutely loving nothing about a "crusade" against gay people. All I've seen is that they don't get special treatment. Boo loving hoo.
It's literally in the article. If you want, you can read about the more specific cases of family values in Russia, but Wikipedia summarizes it pretty nicely.
In the 21st century, Russia began to receive worldwide attention for their legal treatment of LGBT citizens, which has been referred to as one of the worst human rights violations in the post-Soviet era. Since 2006, numerous regions in Russia have enacted varying laws restricting the distribution of materials promoting LGBT relationships to minors; in June 2013, a federal law criminalizing the distribution of materials among minors in support of "non-traditional" loveual relationships, was enacted as an amendment to an existing child protection law.[6] The law has resulted in the numerous arrests of Russian LGBT citizens publicly opposing the law and there has reportedly been a surge of homophobic propaganda, violence, and even hate crimes, many of whom use the law as justification.
What these laws essentially state is that being homoloveual and being on television, writing a book with homoloveuality in it, directing a movie with homoloveual characters, or just being gay in general can get you arrested. 'Distribution to minors' is an intentionally vague description, since it can mean everything from distributing pro-LGBT flyers to children, to just same-love kissing in public (potentially in the presence of children!).
This isn't an overreaction or a hypothetical argument either; it's how Russia actually uses this law. Last year, they used these laws to arrest LGBT activists during a May Day parade, while simultaneously allowing neo-national socialists to participate in the same event without issue.
http://www.washingtontimes.com/news/2016/may/2/lgbt-activists-banned-russian-may-day-parade-not-n/