Such a policy is ridiculous and absurd on its face, because it is contrary to the the fundamental principle of free software, which is that users share information about, and fixes and improvements to the software they use. Must links to CVE entries, for instance, must be blocked as well? How would that help the users running the vulnerable-but-free software about which the CVE had been created?
What about bugs originating in systems where the bug tracker is free software, but which happen to be running on a non-free OS? (How would you know? Why would you care?) To take the point further: should GCC ignore bugs from Mac users, who happen not to run a free OS?
Talk about cutting off your nose to spite your face!