Actually, I think the audience was completely out of order. If the public disliked them that much then they'd vote them out, but don't boo 2 young lads who are making the most of a once in a lifetime opportunity. Very rude and very unfair on them.
I've heard that the audience are told exactly what noises to make and when, so if they boo John and Edward it is because the producers want them to. I wouldn't be surprised if that's not an exaggeration, these shows have a very pantomime feel about them after all.
John and Edward wouldn't be on the show if Simon Cowell didn't want them there. They've been given the "pimp slot" twice in a row now and overproduced dance numbers so that their act isn't just about their singing. I know a lot of people who think they're funny and enjoy their performances, but I bet that would change if it was just the twins and a pair of microphones.
The twins were put into the top 12 with the producers authorisation, I don't believe for a second that Louis Walsh was the only one who wanted them there. The "controversy" increases the media coverage of the show, which increases the number of people who will watch and possibly even encourages people to vote against them when they otherwise wouldn't have voted at all. There will also be people who may not have voted who will vote for the twins either because they're "entertaining in a generally rubbish show" or to "stick it to Simon Cowell".
I'm sure there will be a big difference in the twins performance the week Cowell and the producers decide they've served their purpose. My guess would be first slot of the night and a forgettable song that they have to sing straight with no backing singers or dancing. Trying to show them up will only encourage the sympathy vote, they need to lose the feeling of being contraversial.
I feel sorry for the twins, none of this is their fault. They get told what to sing and how to act on camera and they're just kids who want their 15 minutes of fame. They seem like sweet kids too and in a little over their heads, I'm not sure they realised before the live shows that they would be exploited to such an extent.