Finis snorkel

A few months ago one of the workers in our local indoor pool told me that my son could not use the Finis snorkel in the pool because it "blocks the airway". My son and I both had been using it for months without anyone mentioning this to us. Perhaps as a pediatric ER physician I should understand what on earth she is talking about, but I really don't. About the only scenario I can think of that would be a problem is if someone seizes in the pool and they can't get the snorkel out of the mouth to maintain an airway. Have any of you encountered such a rule in your indoor pool? It was never an issue in our neighborhood summer pool. I really find the snorkel to be helpful with many drills that we do and miss it a lot.