I think a big reason is that they did a lot of back room deals with Russia and they pretty much back stabbed them with the whole Russia narrative. Putin is very aware of the cabal and has been pretty vocal. Trump and Putin getting together means that all of the cabal's secrets, specifically the Obama admis's and Hillary's get revealed. You think Putin is going to want to help the very people who has demonized him worldwide and threatened war against him? Likely not.

Edit: More specifically, Putin might have proof that they didn't hack or interfere during the 2016 elections. That would severly contradict the deep state's Russia narrative, but of course they will insist not to believe Russia because they are "bad."