zxcvbn has problems but your example is backwards. "aaaaa" gets (as it should) low entropy because it is a single repeated character. It is more likely to be used than "rqntd". The major limitations are that it is worthless for estimating entropy of passphrase (which is what it's being used for here) and words not in its dictionary (non english).
That tool generates a random salt, so passphrase cracking time is O(n) where n is the number of files being cracked vs O(1) for Minilock public keys. Additionally, encrypted files are generally still not "public", whereas Minilock public keys likely would be.
Tarsnap does not allow anyone who has your public key to attempt to crack your paraphrase. Minilock does, and in fact you can load all public keys into a bloom filter and crack them simultaniously with nearly the same speed as a single key. The design of this system is simply irresponsible. Saying people will be fucked is entirely appropriate here.
This is a bad cryptosystem which will result in people being fucked. Take it offline. A serious known weakness of zxcvbn is that it will grossly overestimate the entropy of things like quotes, lines from songs, lines from movies, etc.
"the quick brown fox jumps over the lazy dog" has 111 bits of entropy according to zxcvbn.
I think the cluster at the end of July/beginning of August of 2013 was me. I am not entirely sure because it was during BlackHat/defcon and I was drunk. Was a few thousand sampled from the rockyou list? Post a pgp key I have a question for you.