Embargoing is very tricky and often harmful. Attackers know how to catch embargo'd vulns, it's often really easy, like in the case of the Linux kernel. If attackers have advanced notice you're only hurting defenders by hiding things from them.

We know that two weeks before disclosure there are attacks using this exploit. Somehow had clearly figured it out, so hiding it was only going to cause problems.

From what I read the patch is public and when someone saw it figured it out and publicly shared it.