I'm afraid I'd side with the panel on this one. It's not sexual harassment, it's a discriminatory phrase in which sex is a component part. Those are slightly different things. Many women do indeed go bald but relative the population and male pattern baldness it's quite rare. The insult is discriminatory on the grounds of sex.

The equivalent would be calling a woman a 'flat-chested cunt'. Whilst many men are indeed flat chested (because they don't have breasts) such a comment would be considered a sex-discriminatory insult because its usage applies predominantly to women. That's not sexual-harassment, but if you're fired by someone who says that as you're packing up your locker, then they've used a discriminatory phrase and you can instruct your legal team to make a complaint accordingly.

Cunt is not a problem because here in the UK it isn't a gender specific term, though using it to dismiss a subordinate employee would almost certainly constitute misconduct. Nevertheless, we love saying it. You can blame Jason Statham and Steven Berkoff. cuntcuntcuntcuntcunt! Hehehehehehehehe