[amichal]

guessing... Touch tone phone keypads dont always show q and z. I suspect that some older JetBlue system allows you to use your password via a touch tone system (with a vastly reduced keyspace)

[elsporko]

That would also explain the last rule:

Cannot contain special characters or symbols (such as !#$@*, etc).

It seems to be geared toward those with cell phones but not necessarily 'smart' phones (with full keyboards).