The endorsement of Skaller was unsurprising, given that he previously was CBID president. But Simon, according to rivals like Ken Diamondstone, did not have the strongest reform credentials among the seven candidates.
I wasn't there for either the public or private segments of the discussion (I'm not a member), but I suspect the endorsement of Simon was in part a strategic move. Like most of the candidates, she's certainly qualified.
She's also a woman, and thus has the strongest chance among the "brownstone" candidates to beat Stephen Levin of Greenpoint, who's county leader Vito Lopez's chief of staff and seen as the machine candidate.
Skaller sides with Develop Don't Destroy Brooklyn on Atlantic Yards; Simon has been critical of the project but has been associated with the milder position of BrooklynSpeaks. Several CBID leaders are well to the "left" of BrooklynSpeaks, but, obviously, the Atlantic Yards issue wasn't dispositive.
By the way, the CBID questionnaires (including archived ones) are a good way to get a sense of the candidates' positions on a host of issues.