I doubt you or anyone here will disagree with me, but it still needs to be said: that man was 100% in the wrong.
Asking for a bunch of extra dressing is one thing, but asking for “as much as possible” means when they actually go out of their way to accommodate you, you better show you’re ecstatic, thank them, and tip them well. I don’t care if you have to lug a bucket of dressing home, maybe you’ll learn that words have meanings…