Hi businesskickoff! Welcome!
One of the first questions I ask my clients about getting a website established online is, 'What's the purpose of the website?'.
Believe it or not, small business owners have a hard time answering that question. After all, they have lasted this far without one, right?
Anyway, have you considered asking just that? What's the purpose of the blog? I think the blog can stand on it's own. I fully understand you want to do the best you can and see it 'take off', but have you considered that maybe he/she just wants to 'see it online'??
Also, have you considered showing them a Google search for the 'topic' they are working on?? When you do that, I think it will be clear to show them how many other sites/pages are in the same 'space'.
On the other hand, this project just may be one of those things that are on their 'bucket' list.
Hope this helps! Good luck!