I would be very much against that personally. On the site this report is coming from, TL4 users do pin globally, and have reasons for doing so. This was an innocent mistake that the user realized and was cleaning up. We have a definitely need for users to be able to pin (including globally) but not get access to /admin or /flags.
Edit: disabling TL4 global pinning also will not do anything to solve the original issue, which affects site staff too.