I hope I can help with this by sharing my own story.....

My GLO is a professional music sorority. However, on my campus (when I pledged at least) they were very active socially, and when I rushed, the music aspect was only mentioned minimally and the "professional" aspect never.

I, personally, have almost no interest in music. I barely even listen to the radio. But I did the philanthropies that came along with it, and in the process, learned to appreciate how much it means to people that do.

I think, especially if your GLO is going to be the only organization around, that it is great for your friend to pledge. I am sure s/he will be a valuable member of your organization, even if they are not looking into the law field. Perhaps s/he will even learn something about it and consider it in the future. And finally, it never hurts to have someone with different interests to keep your group from being too stuffy (as my chapter of my GLO is now)

Best of luck to you with your new chapter!