DVC is deeded real estate. It is just like your house. Would you make your son an owner of your house?
I am not saying do not do it, but, as a PP said, think long and hard.
Sounds like you have a great relationship, but, WHAT IF you become estranged? Now you cant sell it if he wont sign off on it. And even though you paid for it 100% you might have no recourse to get him off of the deed in such a situation.
What if he gets married? Declares bankruptcy?
So many things could go wrong to benefit so little.
Not saying do not do it, but put some serious thought into the idea.