It's a good point you make but the hotel would be in breach of current law if they did put their stance. It is simply against the law in the UK to be that discriminatory and offer a service. It is blatatnt discrimination
How odd that a dog would be okay on the premises but they were not welcome as two humans who loved each other. And to show balance a Hotel in the UK has been chided today for putting a notice outside saying "Poofters welcome!". You see even implied bigotry is not okay... ever.
You watch old films and documentaries and you see notices in hotel and B&B windows... no blacks, no Irish, pets welcome, that kind of thing. Heaven forbid we ever see those times return BUT the thinking that underrpins some of those notices is still there. It's wrong and it's illegal. Rightly so too