If there was a systematic bug in receive or send where a certain string of data corrupted a buffer allowing for code execution, exploiting it remotely would be simple if there's any code on the machine using that syscall.
I'm not saying this is a likely bug, or even something vaguely reasonable, but it could totally be found with local syscall fuzzing, so local priv escalation isn't the worst bug you can uncover.
I'm mostly being pedantic here.
I don't think anyone thinks the sky is falling. To me what's interesting about this is the approach Jesse and Tim took, and how quickly it generated very straightforward panics.