Your users used the software to protect them, or even paid for it. Now this "Dave" can crack files generated by this shareware. Maybe "Dave" had a genuine national security situation. But was it really? What if Dave just wanted to prank the author, during a boring afternoon? What if it were a couple of guys parked outside who hijacked the phone system, so even if you call 411, it would route to their van outside? Or what if Dave already did the same demand to dozens of other security vendors, effectively having the source code of all encryption software? And even if it was a national security situation, what is the legal basis of giving up source code and keys?
What I get is "I was just a regular computer programmer and overnight, I was actually important enough to be useful for the NSA"