Actually, it won't. His grandchildren will be long dead by the time the brute forcer gets even close to finishing. By that time, the universe would have become almost a totally lifeless husk. His grandchildren, along with many other people from this age, would become assimilated into the universal meta-intelligence, and become reborn as newborn star-children. Then, it would finish.
In any case, I really don't like passwords. I have three passwords. One is short, for the crazy websites that, for some reason, require short passwords (shorter than 12 characters? Why?). One is medium-length, and one is a high-security password that I use only for my most important things (not that I have a lot of important things; I guess I would use multiple passwords if so). This would already be pretty bad, except there are all these websites that force you to put numbers on your passwords and do these other ludicrous things and arrrrgh
Also, I'm basically computer-illiterate - I don't quite understand how one would go about testing passwords in the first place, but this subject fascinates me. I mean, wouldn't you have to physically type them in? Would you use some sort of floppy disk or CD or something to start in a different thing, and do it that way?