I doubt it. For one, how could they expect to distribute it in a way that a bad guy was more likely to download than by going to the official site?
But also, if they did want to do that, they could probably backdoor it pretty easily just by patching the binary a bit. Reverse engineering and changing binaries is way easier than cracking encryption, and they probably have some of the world's top reverse engineers.
The fact that they asked for an existing algorithm backdoor, among other things, makes me think they really were trying to crack at least one thing encrypted with it. As for whether it was to deal with a time-critical situation or whether that was just a confidence trick to make him more likely to give up the code, who knows.