Security through obscurity is a terrible decision anyway. Just so we're clear on that part, as far as Crytek goes, ouch, wouldn't wish this on them. If an internal leak however stops them from making PC games, I don't see why the whole PC gaming scene has to suffer because they can't keep their devs/distributors etc. in check.
However, if source code was released, I might be curious to check it out from a technical standpoint, assuming the comments are left there, otherwise it's really worthless, since it's identical to something you that's run through a disassembler.
edit: I don't think this will hurt sales or anything much, I mean people who are going to buy it, they're going to do it either way. Assuming Crytek would have a decent PR department, I bet this could be spun into their favor. I'm predicting it won't.