I'd stay away. I checked HNJ's website to see if they've tested those helmets with gimmicky ears (they also do horns and batman apparently). They've published zero testing for safety, wind resistance, or anything at all related to those ears.
I wouldn't trust the single most important piece of safety gear to a company like that. Go with a more reputable brand, and take the other commenter's suggestion to attach foam ears if you really need that aesthetic.
Simply put, it's just not worth the risk.