Hmm, I'm not sure I agree with where you are going with this.

The combination of Beaker-user-local_hostname ensures that the SSH key for the local user doesn't get recreated each and every time. Adding this will just create more unmanaged security groups, being mindful these never get cleaned up either (except manually).

Security groups are not a great indicator of identity anyway, if you want that use the "Name" tag probably.