Being a hardwareengineer myself I have to agree with you, it does seem overly optimistic to move the entire HAL from phase5 hardware to A1 in just 2 weeks.
Being a softwareengineer myself I have to say to you, that it depends on the way the HAL is written. A well written C++/ASM code needs few hours (the C++ part) and few days (by rewriting the ASM parts), if they are not so silly to put too much ASM code inside ( the times of C2P algorithms which were better from others only by CPU cycles are gone forever , yes, and the one from 'Kalms' was the best

). And I doubt, that it is written in ASM, because one of the goals of the HAL is to be portable, so you will have to rethink it ten times ,what you will write in ASM, and what not, if you are a designer.
re
Treke