It's nice that the game is complex and thus allows complex opinions and complex reasonings, it's a pleasure for me to read them.
Though I haven't been present here while og Stomachache discussion or even read it, I have a smol reasoning to share as it was my first post about it here and having looked at bigger and deeper things about the game for awhile my vision of it haven't faded.
So, green Stomachache is a good player's trap.
Sel is an author of specific disposition toward players.
Thus, looking at the event a bit wider than characters and plot, the player's decision is of meaning and of assessment. Green is good? Yep, tons of justifications for it. But as for motivation behind this decision - it's compliance (with the plot, 'characters growth', 'greenness line' etc.), could even be assessed the same as local title of lilcordians' - sycophancy towards the author, the plotbearer. So, yes - going green is going canon, going right, going good. And as of the whole community - yes, of course. But personally? It's like differences between Western (primacy of person) and Eastern (primacy of society) worldviews, it's somewhat subtle, but looking in general - there it is.
So, if we are talking about Sel's inclination towards 'punishing' players for specific character traits behind the decisions they make, I think compliance may surely be one of those. Moreso considering philosophical depth and educative tendencies of the game. And even moreso, with Sel's trait in liking to have sadistic joy in toying with person's (character's) freedom of will deprivation, fun in illusion of free choice as in 'This Town Has Two Halves' or the one with Molly, somewhat his bruised ego's god's complex.
And I see the detail to prove it - you technically can't go red on Stomachache as it becomes 'different' event in such case.