as a founder and an engineer.. you are being naive. You know how many times we hear, "I have a billion dollar idea, all i need is 1% of xxx market". Yes we all hope our startups will be successful, but in the end engineers and designers have to look out for our own best interests, as the odds are stacked against you and more than likely you will fail. While your idea has some social proof ( http://www.maven.co/knowledge-marketplace , http://www.liveperson.com/experts ) , its very hard to convince people your idea is good.. especially if its an extremely new idea, and second hard to hire the best at lower than market value, especially if you are a first time founder with no experience raising funding ( the TC article does you no help either).

You should see if he would be willing to contract with you, while allowing him to work another job and possibly give him equity incentives along with pay.