They did extensive due diligence on Demidov, it would stand to reason they would have done the same on Michkov.
Friedman already reported that Michkov played the process with his agent to get to Philly. I think they might have been the only team to know that he could get out to the NHL 2 years earlier.
Watching how Rotenberg is handling Demidov, I can easily see how a team would be apprehensive about Michkov developing there for 3 seasons.
On top of that, the culture buzz word they used for Reinbacher, I feel like also was a bit of messaging that they knew Michkov didn't want to be there and had a priority to go somewhere else. I don't think that is the type of person they wanted to bring in, someone who explicitly didn't want to be there.
Then you have the rarity of the Reinbacher profile, the fact the Hawks did the same thing with faced with a Demidov vs RD dilemma, and it's easy to see why they made the choice they made.