Some Valyr were displeased with Michael's demand, but interestingly enough, nobody rejected the use of Mind Reader after he made a Soul Contract that stated that he wasn't going to spill any of their private –possibly dirty– secrets and that he wasn't going to use his Soultrait to manipulate them.
The result of utilizing Mind Reader on the Valyr was pretty one-sided. None of them were traitors. The Valyr didn't even think about betraying him, let alone the Valyr Lordess. The majority of their thoughts were filled with revenge and the desire to tear apart some idiots, aka the Council of Xylon.
It was a good thing that nobody was going to betray him or the Valyr Lordess. However, it was also surprising, and oddly boring compared to the things he had to go through in the past. It was unusual that he wasn't thrown from one hellhole into another. Luckily, he didn't say that out loud. There was no need to jinx it.