So, then, your position is that Viktor has, basically, no value to Vlad at this point?
That could be, I suppose, but he might have connections to a list of non-government suppliers of arms and still can be an effective middleman with his old pals. If he has no value to Vlad, Vlad would have probably let him enjoy his time in an American supermax until the sentence expired.
Clearly, there seems to be something going on that we mortals cannot discern.
It's also a possibility that overworked and underpaid prison guards could have been convinced to leave the room during a prison visit or two to facilitate private conversations. See Jeffrey Epstein, for example.