As I've mentioned in a comment to another post, it's probably fairer to say that "adjective" ~ "noun" form ends of a spectrum rather than mutually exclusive categories.
However, on balance, reasons for saying that "points" is more "noun like" in this case would include:
- the fact that "points" is marked as plural, whereas e.g. the plural is not possible in "a yellow/*yellows victory"
- the prosodic difference between "a points victory" vs e.g. "a clear victory"
- the ungrammaticality of "*the victory was points" vs the grammaticality of "the victory was clear"
- the ungrammaticality or oddness of "*the score, points victory" vs the grammaticality of "the clear, resounding victory"
- combined with the observation that canonically "adjective-like" words go before canonically "noun-like" words, the observation that "a clear points victory" is grammatical, whereas "*a points clear victory" is not.
None of these obesrvations on its own would be a "smoking gun", but combined, they suggest that "points" is towards the "nouny" end of the spectrum in this case.