The recipient of this email responded in the comments of the post, and she sounds pretty genuine. People have preached LinkedIn to us 20-somethings since we started the job hunt junior year of university. This woman literally offers her network as a service to people, is it really that out of hand to assume that asking her to connect on LinkedIn would be a big deal. After all, she had just applied to be a part of this job board.

Now, I think that the actual message of the response is fine. If you don't connect with people you don't know, that's fine. You can say as much, but going off a rant is just a waste of bits.