It was exploited publicly even before the wide publicity following your post so the ultimate negative impact that you may be imagining, is actually quite small. Once it is publicly exploited the benefit of coordinated disclosure delays is hard to square with the risk.
While it was exploited publicly, it wasn't until the HN post and especially a video was posted until the exploits exploded - don't underestimate how many eyes are on HN versus obscure darknet forums or private chat channels.
If someone (independently) found an exploit and weren't thinking of the public interest, they would want to keep it secret and for their own use.