WTF? If I remember correctly he gave her the lowest score of all the judge, and he did mention her flat feet. She didn't get particularly high scores, and a 6 with a couple of 7's was about right. Craig seems attracted to the bubbly OTT types, and enjoyed her enthusiasm, which was undeniably visible. Contrary to popular belief, Craig did criticise Lisa a lot. Me thinks you are just confabulating these two ladies because of their size.
She's a big lady who can dance well. That doesn't make her 'the new Lisa Riley', who, by the by, was a big lady that could dance well. That doesn't mean Alison falls into any stereotype. They are two separate humans with no resemblance, superficial or otherwise. They just happen to be fat.
Contrary to DS popular belief, many big people can dance very well and are very actively doing so - just go to YouTube and look up some seriously talented semi-pro's who happen to be 'fat'. Just because, in a rare instance on TV a fat person is portrayed outside of some media bubble stereotype, and is not easily reduced to a mere one liner, doesn't mean you have to go finding your own brand new reductive labels and stereotypes!
She's just a lady who has natural rhythm and musicality, she's also a natural on the floor and her joy shows in abundance - she's the only one who seemed to be dancing, not just 'doing a routine'. She's got some technical issues, but it's her first week, and those may or may not improve. Oh, and she happens to be fat. Her size isn't an issue to her natural ability, and she isn't making an issue out of her size in some sort of identity vote attempt. She's mentioned it once or twice, it's you lot who are mentioning it a lot more than her.