What has to be remembered is that this is the first week and that the prime aim of the mentors is to win the competition.
I think Simon thinks that Eoghan and Austin are his best chances of winning and did give Scott the short straw. 'Cruise ship' 'Karaoke' 'Cabaret' are all words that he uses regularly to disparage contestants, so why he decided to project one of his acts in that mould is baffling.
Having said that, he did sign the Teletubbies and Robson and Jerome and turned them into stars so maybe there's a plan.
The Dannii/Rachel situation seems easier to fathom. It looked like a mentor putting her protégé in her place and showing her who is boss. The issues with Rachel and her 'feisty' attitude emerged at boot camp and I think Dannii has wasted no time in trying to nip it in the bud. Minogue junior took the percentage call that Rachel would not be eliminated by the public or the judges in order to teach her a lesson.
Like a few on this site, I have been to the X Factor Live tour. At one of the concerts, I bumped into an unsuccessful finalist who suggested that their mentor consistently went against their choices (even down to styling and image) and ultimately undermined their chances of winning the competition. I am not mentioning names because it was said in confidence. The only reason I mention this is because a lot goes on behind the scenes to shape our perception of the show and the competitors that we as the public don't see.
I am not a fan of either Scott or Rachel but I do have sympathy for them in the fact that they have no control over all aspects of their Saturday night performance.