I think the reaction of your writer shows more about them than it does about you. When you see a train wreck of fic - and that sounds like one - probably one - maybe two suggestions is about all the writer can handle. I mean, he/she wouldn't put it up unless they thought it was wonderful. So starting with punctuation would be a first step in criticsm - or perhaps backing slowly away . . . LOL. You did your good deed - who knows? Maybe when his/her ego is soothed by time, he/she will grow up and remember a few of your suggestions.