You're putting the absolute worst possible slant on Sergei's later career. In the last seven years Kharitonov has won 10 out of 11 fights that didn't end in a No Contest, with one knockout loss by the hard hitting Javy Ayala.
This is pure Wiki-capping.
As someone who has been a fan of Sergei's and closely followed his career since his days at Russia Top Team in the early 2000s, I've learned to be realistic about his defects in terms of laziness, motivation, and simply being a professional.
Yes, Kharitonov won a bunch of fights against garbage heavyweights, most of whom were as old and broken-down as him, if not moreso.
Mitrione, for being a limited fighter and 41 years old, is a lot tougher and more dangerous than 2017 Sokodjou, 40 year-old Kenny Garner, Chase Gormley, a Joey Beltran with crippled knees, or the other people Kharitonov beat during that "10 out of 11" win streak.
He looked great boxing up and knocking out Roy Nelson before that, albeit a 2018 Roy Nelson.
Sergei looked great against a glorified punching bag whose reactions and timing are completely shot from a combination of age and blows to the head, whose sole remaining weapon is his wrestling.
That has zero relevance to a fight against Mittrione, who won't be looking to wrestle Kharitonov at all, and whose striking is far from washed-up and harmless.
He was coming forward on Vzazgin in round 2 when a phantom eyepoke seemed to happen, but Vyazgin acknowledged it with a hand gesture for what that is worth. I couldn't really see the poke on the replay but it sounds like you are accusing Sergei of faking an eye poke injury to get out of a fight that he wasn't losing yet and I don't believe that to be the case personally.
So you admit to not seeing any eyepoke, even with the aid of slow-motion replay, yet dismiss the idea that Sergei was using it as an excuse to quit against a tough opponent?
I think you're trying to talk yourself into this bet.
As an underdog I think he matches up well with Mitirone at this point, especially since Mitrione was all herky jerky in the brief time their fight lasted before the groin strike.
He is a very tiny underdog. He would be worth a stab at more significant plus odds, but not anything lower than +150.