In the absence of any specific national fraternity policy which forbids helping with a survey... I think this could potentially be a perfectly pleasant public relations exercise and interesting for 
both parties who take part. I don't get the impression (from the academic level i.e. at school) that this is meant to be a torried, deliberately slanted "éxpose!!" 

, more a fraternity experience in the words of men in them; erm, thing (and likewise for sororities).
I see why the reluctance/cautiousness might be there but I definitely think it is being over stressed here and there is the risk of losing out on a good and valuable opportunity to communicate about greek life, outside of a potentially biased media article! I think there is zero chance of her knowingly asking anything "secret", and fraternities are not like the Skulls or something that should not be talked about! 
I hope people will respect this post is just my opinion.
Katy, I'm not in an American fraternity. I would certainly help if I could. I know there are many, many people on here who love being a part of their respective group. I hope some people will come forward to chat to you via an email about their sorority/fraternity experiences. 
 
eta: As this post is just my opinion... 
please PM me if you would like to discuss anything I have said as my intention is not to create a hornet's nest in this thread!!!