Flocke knows that Ben knows that Flocke knows that Ben knows... by Magnus Hanso

Flocke and Ben are actively trying to manipulate each other. Ben is just biding him time, and Flocke knows it. Ben shooting Widmore didn't convince Flocke of anything, he already knew Ben hated Widmore.

Flocke tells Ben he needs him to kill some more people, and then he can have the island to himself. Ben doesn't trust Flocke here, but what is he going to do, start a fight? Not long after, Flocke tells Ben that he is going to use Desmond to destroy the island. Ben, being a smart guy, realizes that he wouldn't likely survive the island being destroyed, so his suspicions that Flocke was just using him are confirmed. Flocke is a smart guy too though, and he knows that telling Ben that he's going to destroy the island will lead to Ben realizing that he will die in that scenario. At the same time, Ben realizes that Flocke is smart, so Flocke wouldn't tell him this unless he already knew that Ben was suspicious and was trying to manipulate him and wanted to make sure Ben would act in a predicable manner.

So at this point, we have the following:

Flock knows that Ben knows that Flocke knows that Ben knows that Flocke is using Ben.

Ben is trying to pull a con on the master himself, or is it the other way around? I'd say that the Smoke Monster is the master of all of Lost's con artists. Either way, Ben will likely need to get the upper hand in this "con war" if Flocke is to be defeated.