I disagree for practical reasons.

These are exotic edge cases which were never sufficiently tested. The resulting inconsistencies or bugs were already implemented more than a decade ago.

I doubt they'll ever be fixed, it's far cheaper to forbid local %SIG

Localizing %ENV may be useful but localizing %Foo:: is already somewhere in the no-mans-land of undefined behaviour (especially local %main:: )

Good luck providing patches though ;)