Please consider this: the code that is there was specifically added by somebody porting Python to OS/2. So if it doesn't work for you, either OS/2 has changed (which I don't think is the case), or you are doing something wrong (such as using the wrong tool chain).

If the change you propose was carried out, it would likely break what works currently. So everybody is hesitant to add this change, unless you can explain it to us: line-by-line, character-by-character. E.g. why are you proposing that OS/2 is a POSIX system? Treating it similar to NT is much more plausible, given that NT was designed as the OS/2 successor originally.