alt Hacker NewsTheir comment would technically be proprietary code since there's no license alongside it, but grishka wrote the original implementation of the reverse engineered code in that mastodon commit in the first place. So I'd imagine it's free game to use it as a reference (IANAL)
Grishka expresses that the code is trivial. Trivial inventions are not covered by patents. I believe, therefore, that a license for trivial code is not necessary.
But if someone knows better I would appreciate any correction. Legal matters are seldom clear or logical. Your jurisdiction may vary, etc etc.