This site refers to "scaffolding offences" intimating that the Scaffolder has committed an offence, he has not.
It would however be an offence to leave the scaffold untied and in an unsafe condition.
I should also point out that the decision on which ties to use on a listed building lies with the client who has a responsibility to both the listed building regulations, and the Scaffolder.
Whilst the Scaffolder may offer suggestion and preference as to tie type and location he need not necessarily know of the status of a buildings listing or it's structural capacity, as such the onus lies with the client who is required to know both the structural suitability and the listing status prior to commencing work.
It is then the clients responsibility to ensure that suitable alternatives for tying are made available to the Scaffolder such as open windows which are in general not acceptable to occupants for whatever reasons. I guess you could always buttress into the street and block traffic?
Having spent the last few minutes looking at the Bath site It is worthy of mention that the two scaffolds marked as no drilling are both unsheeted, That said I see no signs of ties in either (not to say there aren't any)
I was going to write to the Bath Heritage site (contact@bathheritagewatchdog.org ) and offer opinion but from the lack of knowledge displayed on their page I shan't bother.
regards
Alan