These terms, restoration and patina, trouble me no end. I think everyone has had a say (ad infinitum) as to their definition of restoration. Mine is the minimum required to restore a bike to an acceptable level of condition as determined by the owner.
Now patina...I don't know. According to definitions 1 & 2: A green film on copper/bronze & a surface appearance that is more beautiful with age. The objective definition would most typically only apply to copper saddle rivets and brass headbadges. The subjective, beautiful...is in the beholder's eye.
So, does this mean that polishing (using mild abrasives to clean surface) a decades-old original finish, whether chrome-plate, oxidized Al or paint, is a no-no? If one looks at the weathered (to be kind) finishes of some Golden Age Book bikes, it appears better not to touch. Yet, it is well known that polishing also removes contaminants that may be harmful to original finishes, esp oxidized paint and rust. Is a rust speck a sign of character or a blemish to be eradicated?
Perhaps it depends on the bike? Museum pieces probably best left "as-found". A Varsinental...do whatever. Bikes in-between, that's where the conflict presents itself.