IMO, he had just decided the 'Decent Interval' strategy was decent enough.
TY for the link, certainly more Congressional dissatisfaction than indicated. I will note that both Administrations supported the bill, so I'm still not sure who flip-flopped except for the House Republicans (it had failed an earlier vote and Pelosi publically said she'd just wait for the Republicans to cough up enough votes, which they did).
The original point wasn't a party political one, but I think your reaction demonstrates it nicely. What the administrations do isn't the question, its that their tribes convince themselves that their team has been consistent and that they haven't changed their minds... which is what the study was trying to show as well.