I agree with marking restoration with a date.
Absolutely not. Unnecessarily adding anything to an object is considered by all professional conservation bodies as bad as taking anything away from it. There may have been some small justification for dating restorations in a bygone age but not now - now there are paper and electronic records.
But leaving a fecking portal into fairy land is ridiculous!
Yup, in fact it's not only ridiculous it's also unprofessional and totally unethical.