Then they've told you all you need to know. Your only dilemma will be how to let him know. I'd just tell him you need to go it yourself on this one and that's that. And you don't have to tell the rest anything, they'll know what you had to do but will respect you even more for not saying anything more than he's "going his own way".
I envy you the crew you do have and their willingness to WORK with you.