I assumed that it would be being filmed by presenters for the beginning of it, as I can't see how it could be used as an act?
Don't get me wrong, I like Britain's Got Talent but I don't think it should get priority over paying guests. Imagine paying £48 to get in, then being told you can't ride it whilst watching people being sent round it multiple times being filmed? I know I would be annoyed!
(Almost as bad as letting celebs jump a 3 hour queue!)
Why should they have to though? Personally, I'd be miffed if I visited and they closed a ride early for a reason like that, especially if I had paid £48 to get in!