You've encountered a butthole, that's all.
With tech training, it's entirely possible you are a better trained diver than that OW instructor. Her training focused on how to teach a non-diver the very most basic diving skills without killing them. Your training is (or SHOULD be) a lot more comprehensive.
Regardless of skill levels, telling another diver on the boat how to dive is inappropriate behavior. Fortunately it's pretty uncommon. I haven't used a snorkel in years. I dive an unusual backplate and wing with a long hose configuration. I can't remember ever having someone give me a hard time about my setup on a boat. Even touristy OW boats like the ones run by Rainbow Reef. I did have a couple RR DM's ask me a bunch about my setup once, but they seemed mainly interested in learning rather than chiding me about it.
Not that it matters, but using those rollup deals does kind of suck. Have you tried it? I switched to just keeping a fullsize snorkel in a pocket. Best of both worlds.