The fact is, people who watch The X Factor aren't necessarily the same people who will go to see the performances. The acts each have individual fanbases.
Misha and Janet don't need the support of every idiot who believes everything they read and don't believe words coming from the person themselves after the show.
How well they did on X Factor stops making a difference to their careers at this point. Those who are gonna get signed, will get signed, and their fans will go to see them.