I guess it comes down to how much we want to limit the behavior change.  As reported, we know for certain vfs related (vfs and scmvfs), cshtml should not be handled by webpages.  We could target the fix just for that and wait and see if more reports.

If you think the behavior change is desirable across as no scenario should ask for cshtml explicitly.   Then we can go with what you have.   BTW, currently I can do https://<scm>/default.cshtml.   With your change, I won't be able to do it anymore, correct?