where is user of number 51190 in the file?!
This is the most brilliant insight I've read so far. The hacker likely had a login on mtgox and probably deleted themselves before release.
That said, 51190 is in there:
51190 tgibbsz32
tgibbsz32@gmail.com $1$9eZ.kSvA$fshZ6R1jkNtlllW10Sxpp/