Hmm...I know you said "you've never really been interested in all of that" but...i dont think you mentioned why you actually dont you want to be with him?
Or did i miss something? lol!
I think that if youre good friends with him and you want to stay good friends with him, then you really need to be honest with him.
Theres a possibility that, if he does ask you out and you reject him, he may feel upset/angry, but its understandable. Its usually only a temporary thing as it can be difficult to accept rejection.
Just keep being his friend
Its no ones fault, especially not yours, if he has feelings for you and you dont feel the same.
But for now, dont worry about it. Id suggest carry on what youre doing, making sure you dont do anything specific to make him think your into him. But dont be scared of carrying on doing what good friends do with/for/to each other.
I hope everything works out alright