From their perspective, on their project, with the constraints they operate under, bugs are just bugs. You're free to operationalize some other taxonomy of bugs in your organization; I certainly wouldn't run with "bugs are just bugs" in mine (security bugs are distinctive in that they're paired implicitly with adversaries).

To complicate matters further, it's not as if you could rely on any more "sophisticated" taxonomy from the Linux kernel team, because they're not the originators of most Linux kernel security findings, and not all the actual originators are benevolent.