I think what he actually meant is cheap paint + oil will be a nightmare to remove from just about any surface. It may have something to do with why he specifically mentions gloss paint. That may have an added chemical that could contribute to scratching if mixed with oil.

I know only the basics about paint, latex is water based and everything else is oil based as a solvent that would evaporate away and deposit what remains. To remove oil paint you need another solvent. You can't just add water to a latex paint though to get rid of it once that water evaporates.

So perhaps in theory. You'd need to somehow re-hydrate the latex to get rid of it, but oil would oppose any water from getting to it, and make an insane mess.

A friend of mine bought an 88 passenger school bus and I've been helping him fix it up. I think he painted the outside with latex and when I was over there the other day it was snowing like crazy and got really cold outside- and all the latex paint just fell off the glass, metal was fine. If that had been mixed with an oil though, you would probably have to scrape it off while getting rid of the oil as well.

It's just a theory, but remember when it dries you're going to have to do something to get the paint off. Latex paint on glass can be scraped off easily by a razorblade. If you add oil to it, it's probably going to take a hell of a lot more to get it off.