Posting to you is like talking to a Jehovah's Witness or a Mormon here on this forum back when I did so regularly (I still do, but on different sites), insomuch that any random thread will devolve into a million different topics that must be dismantled individually, since all previous lies of the cultist fail.
Now we find ourselves debating a completely random conspiracy theory involving Ukraine supposedly false flagging January 6.
Upon closer inspection, which I have wasted a good half hour of my life on, I have made the following conclusions:
Poor Sergei is not listed on any Ukrainian or Russian news channel. He is not listed on https://inter.ua/en, nor does a search produce his name anywhere on that website.
All references to Sergei appear from two separate camps: Leftist trolls claiming Russia did January 6, all with nearly identical language as that put forward by your random twitter user, with absolutely no links or support for any of the claims. One of these sources complain that he is a Right-Wing Ukrainian and implies he's an Alex Jones fan.
The second camp is from Russian trolls, all of whom make the opposite narrative, accusing him of being a Nazi and a murderer and an agent of Ukraine. Except the images posted don't seem to mention anything other than getting a medal for destroying a tank as part of the Ukrainian military.
Poor Sergei's facebook page has absolutely no reference to any employment to any news channel, or to any intelligence service, or to anyone at all, actually:
https://www.facebook.com/sergey.dubinin.39/about
My conclusion? You are fookin retarded and, at best, poor Sergei was latched on by various troll forces.