Because, in his obsession with Mae/Osha, Sol was flying recklessly and threatening to get them both killed.So, why did Basil sabotage Sol's ship and cause it to crash?
Interesting episode overall. The only real surprise was keeping Mae alive. Interesting inversion, with Mae sacrificing herself, and their sisterhood, so that Osha could become a Sith apprentice.
And that was totally Darth Plagueis, wasn't it? That kind of throws out the old Legends timeline, but still is kind of awesome. Muun Sith Lord for the win.