I don't find the responses rude myself and I think people are too easily offended by perceived "tone". Working with customers, there's no general rule of what customers do and do not find offensive.
Look at it this way, if you're actually ONSITE with staff all around you, why the hell do you get your phone out and start tweeting or messaging someone? If my Mrs is sat in the living room with me on the other sofa and I want to talk to her, I don't get my phone and start tweeting her do I?
What do they expect the social media team to do about it? What CAN the social media team do about it? Do they expect them to somehow make things better with some magic wand from behind a keyboard in an office? If you don't have time to see someone at guest services (at the end of the day I might add) then you can always email a complaint and have it dealt with properly. Whipping out your phone because you're angry and tweeting "Alton Towers is shit today innit PMSL FFS LOL poo emoji" is (justified) venting but I don't understand what kind of response people are looking for?