RT.com has been linked here roughly 30 times, and only once has it been called out from what I can tell (by you and later another member in the same thread, to your credit). Despite that, I can't find a whole lot where people have called Larry King a stooge for Putin up until yesterday, aside from a story back in 2013 about an RT anchor that stepped down over the network's schlepping for Russia.
In fairness I'm quickly discovering that RT has had a lot of success apparently via the internet and through embracing guests that fall outside of the American mainstream, so it does look like a significant outlet for them. At the same time, it's hard to find statistics that reliably show the viewership of Hulu vs RT America. Some sources suggest tens of millions for the former and ten million for the latter, and apparently it's complicated in that RT America regularly licenses videos (albeit not the same thing as licensing a full program like Larry King's show). I'd like to see strong numbers that show RT is the primary source of Larry King's viewership today, as well as examples that Larry King's show is decidedly pro-Putin.
fwiw, I did find a 2013 interview with Donald Trump where King does seem to be pro-Putin, and has Trump go on his usual "America is weak, we need to be strong like Russia" thing. I found another with the Dalai Lama where he says that Putin has been leader for too long. Also finding one interview where he apparently has a pro-Putin dude on saying we should be grateful for Russia's involvement in Syria, and another interview where he apparently has someone calling Putin a "bad guy" (unfortunately ORA.tv is suddenly not streaming for me so I can't view the contents of either). I'm seeing it plausible that maybe Larry King really is a sellout, but it rubs me the wrong way when very few people appeared to care until right now when the MSM reports on it and suddenly this is a no-brainer.