It works all in your favour... you marry him, becuase you love him, if something happens to you, he legally has NO rights over the child unless you are married-so its for the security of the child.
AND god forbid it should happen, but if 5 years down the line he turns round, says it was a mistake and runs out on you both...you can whoop his ass getting child maintenance if you're married.
Stop being so synical. Just say to him he needs to go away and have a think first, then come back with the offer if he really feeels its right for him. Explain marriage is for life, and divorce is nasty with a child being dragged through.
Once he see's the logical side and not the fairytale side he may change his mind.
If he doesnt....go for it, and be happy

but really? You cant lose!
xxx