I think she was actually saying that twelve is too old to be crying like that for sympathy.
You can see the father seems to agree as he is not pleased by him crying like that.
On another note, it probably is a reasonable age for him to be doing so - boys mature slower than girls do, so you can still expect some childish immaturity such as crying over small thing or for sympathy at such an age (though it obviously shouldn't be encouraged).