I guess to be fair I have no idea what kind of lacquer they mean. When I hear the word lacquer, by itself, I assume nitrocellulose lacquer, as that's the one in the US that gets called simply "lacquer." It's what cars were once painted with. It chips and scratches more easily than enamel. Lacquer is easier to apply and faster to dry (and it does in fact dry, not cure). If they mean Chinese/Urushi lacquer, that's a different story, but I feel like they would have specified it if they meant it.
I don't know of any enamel Montblancs, but it is the way it's done in jewelry for a reason. I do know of other lacquer Montblancs, like the Napoleon, but it's clear coated over and consistent, whereas the caps here seem to just have the lacquer exposed since it can be felt.