I don't know of any examples of holds being reinforced with sika at Pembroke previously - if they have been, the sculptor has probably kept quiet about it.
I think this has been done at Pembroke previously. I can’t put my finger on where though; I certainly know of bolt stubs which have been sika’d over and it is well known there have been some acts of downright vandalism at Pembroke historically.
If Von T is competent and wants to sika the hold without making a mess, go for it. Lots of good advice on threads on here for sika’ing limestone - do your research.
As Si hints, do not claim responsibility if you do it and it goes well. Do expect a lot of criticism if you mess it up.
Doing nothing is likely the safer option. One person’s crucial is another’s …