But to me anyway it is a very similar thing--
her body is ready for whatever step reardless of age.
Well, I am not sure I blame her on either count:
Sooooo often kids realize they themselves don't really want to do something once you put the decision in their hands. It is always a guessing game as to what they will do

If you truly let her decide this spring she may decide it is not worth facing her fears about the razor and stay hairy--or she may (with time to really think about it and if/when teasing starts up again) decide she does want to shave after all. It is also possible she does not really want to but wants to be able to tell the other kids that she doesn't shave because her mother won't let her--maybe you can let her know if this is the case she CAN still use you to save face and you will back her up
As far as her being mortified, well this is an age that is easily mortified by all things, especially things relating to their bodies. At her age the fact that none of us knows you irl life may make it worse. As in "You told a bunch of
strangers I'm hairy?!?!"