I think that for some people holidays have started a little earlier, at this time of year support may be slower than usual. Have you followed Namecheap rules regarding the abuse reporting? Maybe they consider your case as Fraud scheme and they will not assist you if report is not made to https://complaint.ic3.gov .

I have to admit it's strange that GitHub is reacted in that way, maybe they remove them, but they find a way to get back. Only thing we can do is to report them again.

Is there any progress in the investigation of your case?