How many?
Michael decided that it might be better to isolate himself from the rest of the alliance members for a few hours. He had several reasons to do so.
First of all, there were still more than 20 hours left before the Flag War would officially end, and they would be expelled from the isolated dimension. Michael wanted to finish extracting the Memory Orbs, SoulStar Fragments, and Soultrait Symbols from the corpses in his possession. He could wait and do it later as well, but Michael felt that everyone needed some time to digest the shocking fact that some Descendants turned out to be traitors.
Other than that, many were also confused about the power Michael had unleashed. He hoped that some troublesome encounters and awkward questions could be prevented by isolating himself for a few hours.