He wouldn't know that (for example) Manchin and Sinema would not want to spend what Biden would (never mind how much progressives wanted) on things like infrastructure. 96 % of Dem Senators support Biden's infrasctucture agenda, so ultimately, all delays fall square on the shoulders of Manchin and Sinema and Republican obstruction.
I don't believe he wouldn't know that, so we'll just disagree on that.