I see. To be honest, to some extent this feels a little like the same kind of weirdness some people might have with, say, late-assigned floaters (unless this is different now in Lix compared to Lemmings). Certain things, be it a beam, explosion flinging, or assigning a floater, can abruptly affect fall survivability, and there are bound to be a few cases where things look a little strange as a result.
Perhaps the problem is that the beam case resets the downward velocity to a value strictly slower than normal falling/tumbling, while the explosion flinging doesn't (or does it)? Just wondering if there's still any sensible case to be made to tie the reset of fall distance based on the new velocity being "safe", for some definition of "safe" that can still include some small amount of downward velocity.
It does seem like unless we completely get rid of the ability for explosion flinging to reset pixels fallen, there will always be edge cases for it that can feel like late-assigned floaters. Like Simon said, it seems difficult to sensibly argue the difference between a 0.0001 new upward velocity versus 0 versus -0.0001 downward, when the trajectories would all probably look near identical when close enough to ground level.
Anyway, looking forward to see what Nepster thinks.