It looks more like they sold code to surveil people using cryptocurrencies, not to steal it.
I'm all for putting light to conspiracies, but I personally don't think they used this to just take the coins. But it must be pretty tempting for both the hackers and goverment employees to just take a well chosen priv key. As seen in the silk road debacle.
Looks like they sold the stuff for anyone, who paid for it. So if somenone wanted to steal Bitcoins, he could use RCS and the modules to do exactly this - among other evil things - in a very comfortable way.