This really isn't a problem between different opinions or knowledge base of "engineers" (Boeing vs FAA engineers)
This is a problem related to a process by which the FAA resolved the differences in opinions without a deeper audit of Boeing's knowledge base.
I accept that the FAA knowledge base is below what the manufactures have. After all the manufacturers have access to tons more experience including development tests and analysis not in view of the FAA. So it was not difficult for FAA management to listen more to the Boeing engineers and how they addressed the means to meet the requirements of the FAA rules..
What we now seem to hear (at least from the press) is that the Boeing engineering community failed to confirm their application of knowledge through the pilots who actually do the test flying. So I have to ask the FAA where is the validation of a process that forces this verification of design intent via the in-house test pilots?