I'm asking for the equivalent of a previously invalid flag, to become valid, ...
IMO, there was an early transition from asking to demanding. Negative comments by some of the top developers did not dissuade you in the least.
If every request to interpret a new flag required significant
involvement, goodness, would it take an act of Guido to get a commit done?
Yes, if a proposal doesn't win developer support, then having Guido as a champion is the best bet.
If you are opinion shopping, then the best so far is Tim's comment which seems to equate to a +0. That would be sufficient only if he cares enough to review the patch, write the docs, test it, maintain it, etc. Perhaps he will, perhaps he won't.
FWIW, last year I had dropped one of my own proposals (relating to a non-unicode use for encode/decode) simply based on respect for Martin's -1. For me, that was more important than the +0 to +1 comments from others, more important than my own use cases, and more important than feeling like I was right. In the end, there was an easy pure python equivalent and life went on.
Looking at the struct feature request, I think it would be harmless to add it. OTOH, it is easily handled in python and will be easier still when the binascii functions get put in. Arguably, the feature is somewhat trivial and won't change anyone's life for good or ill.
So, you have to ask yourself whether it is worth jamming down everyone's throats to get it in after the beta goes out. For my money, the feature request has already consumed more developer resources than it could ever save.