I agree that there should be a board for one cycle ssg runs tho because i personally think they are more entertaining, but implementing that on src would be quite difficult, so it would probably have to be a spreadsheet.
it's a fairly difficult thing to define, but i would say that something is a glitch if it goes directly against what is coded into the game. If you dupe objects by force quitting the game, you are clearly causing a failure in the code, whereas if you just take advantage of an oversight, that's fair game. Save and quit abuse is interesting because spawn invulnerability is intended, but i think it can be categorized as a banned exploit, similar to using /seed in a random seed run.
Your definition of a glitch doesn't really work. There are loads of features with unintended uses, even one cycling the dragon isn't intended, so it's way too broad. Another example of a strat that was debated as being a glitch was eliotex's sprint hunger strat, which easily fits your definition of a glitch, but practically had to be allowed. There are way too many examples of strats that fit in your definition that would have to be banned, e-ray, bed warp, pearl hang, etc.
There was a long discussion about whether or not oneshot is a glitch. It was concluded to not be a glitch. That decision was made taking the previous decisions about classifying glitches into account. Reversing that decision at this point isn't practical at all.