Gregory's ServerMy understanding is that traditionally, judges are supposed to be apolitical and beyond reproach, and so would only recuse in the most dire of conflicts. To recuse just because the defendant appointed you was to admit you were incapable of being fair and impartial, and you may as well resign.
But - given current events, I guess that theory is, at best, horse pucky. One hopes a new set of standards will address this long term - but short term, I suspect we're stuck until the current cases have fully resolved - changing the rules mid-game is a bit hinky as well.