No doubt, Schmukie wasn’t about to allow any defections. The rats didn’t fool around. You are right Mitch is weak. Yes he got the main goals done (no new witnesses and the Acquittal) but Schumer would not allow a punk like Mitt to embarrass their sitting President. No way.
No witnesses were for the benefit of the Senate. Not President Trump. You think Collins and Murkowski wanted to sit there while House Dems dunked on them like LeBron and insulted them over and over? Not a chance. They wanted the trial over as quick as possible fore purely selfish reasons. Nobody was watching, anyway. Witnesses would have brought drama and viewers.
Now the do-nothing GOP Senate will resume do what they do best: nothing. Meanwhile, the House Dems will continue assaulting POTUS and his supporters until election day.
The GOP Senate has aided and abetted the ongoing coup against POTUS for 3 years. Longer if you count the campaign. They are not going to stop now.