I'd heard that before. I spoke with several plastic's installers. I get different answers. But the consensus that I've gotten is:

Plexiglas is acrylic and the usual dodger glass is vinyl. Vinyl is a lot softer, has plastizers which may be damaged or altered, etc. I would avoid Windex on vinly. The most important issue is abrasion -- the soft cloth vs. the paper towel vs. the sponge, etc.

Acrylic plastic (generic Plexiglas and it's successors in patent law) can be cleaned with vinegar and water solution. Old fashioned Windex is just that with some blue coloring. The big issue is abrasion.

If you have built-up a coating of wax that's clouded-up, then you you'll have to do more rub it. You need to strip it off. I think that barring some chemical problem on Neil's glass, I'd take a shot at cleaning off the build-up. THEN I'd wax with Nuxus, or Mcguires, or whatever quality protectant.

BUT I understand that there is controversy in recommendations here. I just am expressing what I would do.