I know, but there was no reason to think it was a parasite, either. It could have easily been anything. That's why it's best to hold off on even trying to diagnose until you've got enough information to make an educated decision.
It's great that you're trying to help folks figure stuff out... that's what we're all here for, right?... but you're talking to someone who's worried about their sick fish, and there's no reason to worry them with an off-the-wall, random response.
Also, like I mentioned earlier, if you're going to make that guess, at least let them know what they should do if it is that, and how they can tell if it is, or not. Just give more information, so they're not so confused and worried.