Don't think that "weird system" would work in practice. That would require using some other tool to open issues, add comments, etc. Frequent contributors could use it, yes, but some user who wants to open his first issue or comment from time to time will likely not want to do that. GitHub has big network effect currently. But maybe some monitoring could be used that would detect API changes, that something is not right (some fields missing or something not having new data for suspicious long time period, for example).

Thinking maybe to experiment with this for JoinMarket-Org/joinmarket-clientserver.