A few days after Blinken announced that Poland would privide the MIGs ,the pentagon announced that the US would not be involved in moving the planes to Ukraine, but these days, as you know, the pentagon is more political than ever. I strongly suspect that the Biden gang knew that the pentagon was going to veto such indirect US involvement in the air war. Maybe somebody at the pentagon convinced the Biden gang that it could backfire, or vice versa. They didn’t want Poland blaming Biden.
Too late > IMO