I'd say take the advantage he's giving you. If he gets pissed that he's getting collar choked or that you're slipping out of submissions because he can't hold on to you, maybe he'll change his mind about rolling in the gi. Some folks just need to SEE where the advantages and disadvantages are; telling them until your blue in the face just doesn't work with some folks. If he gets sick of being gi choked and arm barred all the time he may well see the light.