It's a career positioning thing, not a like/dislike thing
The conclusions are somewhat flawed, I think...
It's not a measure of how well developers like a particular language. It's a measure of how beneficial they think it would be to add a particular language to their CV.
It's a career positioning thing, more than a like/dislike thing.
On their like list people will put the most hyped technologies of the day (because they want to be on the correct bandwagon, career wise). On their dislike list they will put what's perceived as "old and boring". Things that they think might hurt their careers, rather than advance it. That's what this measures, really.