Yes she could have been a sorority woman but I'd hope that wouldn't be her sole reason for not mentioning the greek system. That would be unethical
My reason #2 would cover that justification just fine, or so I thought...
(see above)
Of course if she was a sorority woman she should have included some text to the tune of "Binge drinking isn't limited to fraternity and sorority members, it is a problem facing all college students". Of course that study (another debate entirely) has figures that would tell you otherwise....
I'm happy with it though!