Trump did not bring the suit, so I don’t think the justices needed to recuse themselves. Stein has said it was not about Trump, but about ‘honest recounts’, so again I see no reason for the MI Supreme Court justices to recuse themselves just because they were on Trump’s top 20 list of possible Scotus picks.
His reason for recusing himself is
"... in order that the decision made by my colleagues in this case will not be legitimately challenged by base speculation and groundless innuendo by the partisans in this controversy and beyond."
The statement is a good read. He blisters the federal judge who ordered the recount to start.
I agree, but the Justices caved.