What channel was it on? You can always lay a complaint with the Broadcasting Standards Authority for that particular channel. However, it WAS 10pm, which is after the AO programming start time (usually 8.30pm). I've had a look at the BSA guide and it doesn't sound like the TV channel breached any of the rules concerning AO programming, so your complaint is more with the airport than the TV channel.

Was there someone around who could have changed the channel? I think that's what I would have done if I'd been uncomfortable with what was on, after asking the other people around me if they minded. Or give the airport a call and tell them what you noticed. Perhaps because it was after 10pm they didn't expect children to be present and thought it would be okay to have the TV onn adult programming. Or perhaps they just have the TV on one channel all day long and don't really pay attention to what's on late at night.