I had a similar situation, what I did was get lots of books on homeschooling and sit and read them when I was around DH (actually it's all I read about and looked at on the internet for months) Then I'd read out interesting bits to DH
Things I focused on were the academic performance of homeschooled kids and the "socialisation issue" It didn't take long to get him to agree to a trial of it and after 4 months he is a huge fan because of the changes in our son.
Plus we both get to have a hand in his education. Because I was feeling a bit out of my depth with the Flight unit, my scientifically minded DH took over and they are building planes and all sorts of other cool stuff.
So perhaps you could sell it to him as an opportunity to be more involved?
I think that you need to find out what exactly your DH is concerned about and then you can address it with your research.