In my experience, adhesives can be made from - and therefore be reactive to - alcool or petroleum-based solvants. BUT "plastic" and "vinyl" can be a generic term for a lot of different yet similar materials, which may or may not be reactive also. YOMMV.
Therefore, other products can be tried to work out the gum residue. If "rubbing" alcool (in whatever concentration) is giving you a tough time, try kerosene, acetone or methyl-hydrate. Try it on a small unconspicuous area of the visor and see if it attacks the "plastic". Let it sit for a while and only when you are positively, absolutely sure it is safe, soak a Qtip and try to lift-off a nail-size chunk first. Use a diswashing scrub pad on stubborn areas, never steel wool.
Once the best part is gone, you can finish it off with a less aggressive product to avoid exagerated discoloring. I am thinking that the OEM stickers are affixed using a heat-activated glue and this would explain why they are so tough to get rid of.
I'm currently awaiting my very first TDI and I will post the results of my own experiments within a few days of its arrival