Heh, on further looking, I now know why this seemed familiar. subscription_manager/release.py:ReleaseBackend._is_[correct]_rhel does a slightly more exhaustive version of this. 

In that particular case, it's for finding the right rhel variant to look for "releases" for, but it also does some cross referencing against the contents available in entitlement certs. 

That might be overkill for this case [I think for this case, a simpler more conservative approach should be fine]. But it at least means it's probably worthwhile generalizing that code a bit.