Simple, the FAA face an existential crisis as the de facto global regulator because of the MAX fiasco. It needs to save Boeing from itself to maintain this global power.
Another single commercial flight controls related MAX accident and the FAA's reputation and global power are toast. It could save the FAA or Boeing, but not save the FAA
AND Boeing.
I wonder if there is a larger power play here. If the FAA are not seen to put safety above pure commercial interest, other regulator will not feel bound by it's decisions to knock back a new type certification from say, a
Chinese manufacturer without tit-for-tat retaliation. But that is just speculation, divining the tea leaves.