I dunno. To me it seems like if a web server can't deal with 700 simulatenous requests it should probably call it quits. They're of course within their rights to just block the connections but it certainly doesn't look like a denial of service attack to me. Submitting a link to HN probably causes even bigger traffic spikes.
700 simultaneous static requests certainly. 7,000+ in fact. Even 700 average requests for dynamic content. But each of those request was to clone a repo which is not an average dynamic request: each require a fair amount of CPU time (and possibly IO thought hopefully the server(s) have enough RAM for cache for that but to be the case).
Sure, but even if each clone tied up an entire core of their Epyc 7402P for 5 seconds (which seems pessimistic to me) the entire traffic spike would be over in 2.5 minutes.