I agree that this effectively counters the lock and door analogy, and that it's better to avoid these analogies all together when making the case for strong encryption.
Another line of argument is to emphasize the extent that our digital economy and national security rely on strong encryption. If you outlaw it, then all of our online banking and shopping, corporate and government secrets, and more are vulnerable to hackers and foreign governments. And just as the conservative gun advocacy argument goes, outlawing it won't necessarily take encryption out of the hands of criminals, only law-abiding citizens.
Another line of argument is to emphasize the extent that our digital economy and national security rely on strong encryption. If you outlaw it, then all of our online banking and shopping, corporate and government secrets, and more are vulnerable to hackers and foreign governments. And just as the conservative gun advocacy argument goes, outlawing it won't necessarily take encryption out of the hands of criminals, only law-abiding citizens.