I've noticed recently historical works being handled differently depending on the materials. I think there's been a revision in the protocols: Maybe the white cotton gloves are mechanically harmful sometimes? I doubt they let somebody do it who just fixed their bike chain, but if you wash your hands before touching it's possible for parchment, it's not that big a deal.
https://library.pdx.edu/news/the-proper-handling-of-rare-boo...