I’d say it’s nearly as secure as

basic authentication. If you restrict deletion to admin users and use role (or group) based auth to restrict that jellyfin admin ability to people with strong passwords in keycloak, i think you are good. Still the only risk is people could delete your media if an adminusers gmail is hacked.

Will say it’s not as secure as restricting access to vpn, you could be brute forced. Frankly it would be preferable to set up rate limiting, but that was a bridge too far for me