Pretty sure two wrongs don't make a right.
The unsafe planes should definitely be grounded but that would be expensive.
Just because we screwed up before, and exempted planes, doesn't mean we should knowingly continue to ignore danger.
Even if you disagree with this mitigation, every time a new MAX 8 rolls off the production line and enters service, the problem grows larger. Why is this okay, but not with the same for a MAX 7?
Again: either the mitigation is effective enough for MAX variants, or it’s not. I see no reason the two variants should be treated differently here.
[edit- the fact boeing can extort congress is scary]
No it is not. Here, you are doing just the normalization of deviance I'm talking about.
An airplane is parts, and an airplane is a system. Just because you use part X in system 1 doesn't mean a mitigation strategy for part X works the same in system 2. For example system 2 (or the MAX 7 in this case) could also have an addition dysfunction in cold weather that by itself is low risk, but when coupled with this procedure now represent a significantly higher risk of loss of aircraft event.
This is the the kind of problem that shows up in new/changed systems when accepting risk from previous systems at their previously measured outcomes.