Speaker Nancy Pelosi chooses her words very carefully. It may not have gotten much attention in all the shouting today, but when she said she might hold up sending the Articles to the Senate, she did NOT make that contingent on there being a fair trial. Roll Call reports on her statement last night:
The California Democrat said she cannot name impeachment managers to present the House case to the Senate until she knows what that process will look like. The impeachment managers, once named, are the ones who will transmit the articles to the Senate.
“It’s difficult to determine who the managers will be until we see the arena in which they’ll be participating,” she said.
She wants to wait to see what the process will look like, to help her decide what managers to send. But she did not actually demand that the process be fair (her lieutenants did, almost certainly in coordination with her). As I read this, she did this deliberately so that McConnell can’t force her to delay delivery by refusing to have due process.
Right now the Senate doesn’t have a process (due or otherwise) set up, so her position makes perfect sense, and leaves her lots of maneuvering room when McConnell does make his move. Which leaves McConnell caught between his desire to keep the country from hearing more evidence and to keep his caucus from having to make commitments, and Trump’s insistence on getting this over with so he can claim to be vindicated.
She might also be expecting SCOTUS to shortly uphold the rule of law, though that is not a given, unfortunately.