Earlier quoted context omitted.
Honest question. Submitting these types of bugs only to get a: "we have determined it is known low risk issue..." seems like they really don't want to pay for someone else's time and dedication in making their product safer. If they knew about this, was this disclosed somewhere? If not I don't see them playing a fair game. What's the motivation to do this if in the end they can have the final decision to award you or…
Security disclosures are like giving someone an unsolicited gift. The receiver is obligated to return the favor. But if you buy someone non-refundable tickets to a concert they already have tickets for, you aren't owed compensation.
In this case, the spot turned out to be a freckle, which everyone involved already knew was a freckle (since it was documented), and if anyone owes anyone anything, it's the researcher that owes github for wasting their time.