A proof of concept is a very standard thing to include in a disclosure, almost table stakes nowadays because of the amount of bad reports. Once there's any disclosure there will be exploits developed and published anyway, it's not a meaningful difference.

Bashing on the reporter is pointless feel-good. This is a massive vuln. It was 4 weeks after Kernel had a patch. They had no way to know if others parties had also discovered the vuln. Lord Knows how many millions of systems could already have been rooted. The reporter is not their minion.

If I call 911 to report a fire at an oil storage facility - and they ask me to alert the hospital, then phone the neighboring county's Sheriff Dept., and then...yeah. Either I'm way out in the sticks (and known to/trusted by the 911 operator), or else the 911 service is run by children.