For me here, the issue is not about aimer as much as que vs. qui:

 Que vs Qui. As a relative pronoun, que is a direct object (person or thing), and qui is either a subject (person or thing) or the object of a preposition (person only). * Unlike when they are interrogative pronouns, in which case qui means "who" and que means "what."

The question is about the use of the interrogative pronoun, and what that implies for the application of the verb aimer.  It is my understanding from reviewing the various uses for aimer is that LIKE is applicable to things and situations, whereas LOVE applies basically to people and pets. 

So, in Qu'aiment-ils the QUE is WHAT, then we are probably discussing THINGS, and what does aimer mean when we discuss THINGS?  LIKE?  

I do not agree with the Kwiziq answer, if I haven't completely forgotten why we are discussing this at this point.