Because I'm in a piling-on mood: know what else is silly about Wu's crypto SSNs? A Social Security number has to last for a lifetime - 100 years at least. So far, we've never had an encryption algorithm that's been good for 100 years, let alone a key size.
In 1977, the year John was born, the state of the art was
DES. Now, in The Current Year, cracking DES is something security researchers do for fun in their spare time.
To which one could say "Fine, we'll just make people update their keys and algorithms as needed." But what do you do if they don't, lock them out of the system? Who's going to be the one to go around to all the old folks' homes and tell them that they need to create a new set of keys because someone invented the hypercosmic quantum computer and the old ones are now too weak?