I know you've studied Vinaya more than I have, so I'm prepared to defer to your judgement to some extent, but in light of all the different "early schools" and their various Vinaya compositions, it's hard to put much stock in any of those early traditions as being in a position to definitively define the "spirit" of the rules within their varying rule sets.
For that, they must in turn defer judgement to the Buddha, and unless they are the Buddha, they have to accept they have only received the letter even if they'd like to each think (in their own different ways) that they have actually grasped "the spirit".
"Do not force others, including children, by any means whatsoever, to adopt your views, whether by authority, threat, money, propaganda, or even education." - Ven. Thich Nhat Hanh
"The uprooting of identity is seen by the noble ones as pleasurable; but this contradicts what the whole world sees." (Snp 3.12)
"To argue with a person who has renounced the use of reason is like administering medicine to the dead" - Thomas Paine