Interesting about this rumor coinciding with the roster moves though.
The roster moves are logical due to salary cap reasons. It's completely predictable that some people might try to interpret the moves as something more than that.
Every time something occurs with "suspicious" timing, there are conspiracy theorists out there ready to leap at the conclusion that there is something deeper going on. (See, for a recent example, those who immediately jumped on the notion that Hillary Clinton was faking a head injury.)
It's pretty easy to see how someone might combine Ainge's known interest in Cousins with the opening of roster spots and report as fact the speculation of a source that the two might be related. If it was believed Ainge had no interest in a deal with Sacramento, then a different rumor with another team would have popped up.
If there is any truth to this rumor, I suspect it would be from a source within the Kings organization who finds the offer underwhelming and wants to see another bid from a team which can offer a better draft pick as part of the deal.