the linux kernel team is in a 10000% better position to communicate to and coordinate their downstreams. it seems completely backwards to me to suggest that the reporter should be responsible for figuring out every possible downstream and opening up separate reports to each of them.
the kernel team should have a process/channel to say "this is important! disclosure is in 30 days" that is received by distro security teams. because this is not the first or last time the kernel will have a local privilege escalation. hoping that every reporter, forever in the future, will take the onus on themselves is a recipe for disapointment.