Getting rid of Xavier and Casey was surely part of Dan and Mat's game anyway. Cross house alliances like this are usually all about getting others to get rid of members of your own alliance so you don't have too, with the bonus of protecting yourself at the same time. Casey was probably just collateral damage but Dan and Mat needed someone to get Xavier out for them before Xavier worked to get them out.I don’t think it’s reasonable to expect the agreement they made during the musical chairs challenge to extend to all of their allies to. That would be pretty arrogant to expect Chad and Sophie to play Dan and Mat’s game for them.