A grand jury hears just one side of the story. Prosecutors use a GJ when they don't have solid proof of wrongdoing, but just think that there's something going on.
I don't mean to sound snarky, but: that's because they hire people who know how to merge linked lists or reverse words in a string or (insert interview problem du-jour) ; they don't hire people who can really solve real-world problems.
I may sound old when I say this, but my impression of interviewing there was that they're just a bunch of kids who like working on 'cool' or new things, and don't really care much about the real-world impact.
No, this is not sour grapes; I was recruited for my skillset, but was really disappointed to be tested on bullshit problems; I pointed out specific issues with their site that needed fixing and how they could be fixed, but it didn't really matter to them.
That lawyer is based in New York. It depends on many in-person meetings you need with him. But as far as filing patents, that can be done from anywhere in the states.
As someone once said, you can get a grand jury to indict a ham sandwich.