What's in a Designation?

So a barkeep is taking his landlord to court over the following lease clause (problematic part in bold):

The leased Premises shall be used by Tenant as a restaurant and bar. It shall not be used for adult entertainment and shall not be operated as a gay or lesbian bar and / or restaurant.

On the one hand, I have to take the landlord's side in the specific dispute. If the guy wanted to run a gay bar, he should have leased another property, or driven a harder bargain with the landlord, refusing to sign unless the clause was removed.

On the other hand, I just don't see how the clause is enforceable.

What is a "gay or lesbian bar?"

I've been in a number of gay bars, but not once have I ever seen one identified as such on its signage, in its advertising, on its menus ("welcome to Bob's Gay Bar, here are your gay food and beverage selections"), etc.

Yes, I knew these bars were "gay bars."

In at least one case I knew because the (gay) pizzeria owner I worked for warned me that I'd probably get some wolf whistles and a friendly pass or two (I was younger and better-looking back then, and yes I did) before sending me to deliver pizza there. In other cases, I was going out for drinks with gay friends and they specifically asked me beforehand if I would be comfortable in a "gay bar."

And I probably would have figured it out pretty quickly in any case (e.g. one club had a drag queen talent show every Saturday night).

So far as I can tell, a gay or lesbian bar is a gay or lesbian bar because gay men or lesbian women hang out there. I suppose the bar in question might advertise in local LGBTQ publications and so forth, but I bet a lot of not-specifically-gay venues do so as well.

So other than "gee, you've got a bunch of gay and / or lesbian looking customers in here," what precisely would the landlord hang his complaint on vis a vis that clause?

Is it a "gay bar" only if 100% of the clientele are gay? Does it become a "gay bar" as soon as the first gay customer walks in (and what if he doesn't admit he's gay)? If neither of those, what's the threshold ... 90%? 10%? Somewhere in between?

The whole thing seems kind of stupid to me. But it's an excuse to embed a video I like, so ...