See, if this was just a cosplay type thing I'd be like "Oh, that's super cool! And those tails! So pretty and awesome!". I'd even be impressed by the woman for getting a job at an aquarium and using her hobby to teach kids about the ocean. That's actually really cool. How many people get to do that sort of thing? Not many.
Hell, if I had $3000 lying around I'd get me one of those tails and learn to swim in it. I bet it's awesome.
But when they start talking about how they "identify" as merpeople and that they consider their tails a prosthetic that makes them feel complete because they think their legs are weird... That's were they lose me and go from cool to really really not cool anymore.