"Command" is a very common issue when instructing. On the one hand you are trying to teach a skill and on the other you are trying to develop a mindset (part of airmanship). The most regular occurrence is when a student knows he/she needs to go-around but then asks you whether he should do it or not whilst you 'plummet' towards the wrong bit of runway.
Your problem appears to be a variation of this. You are 'checking out' the pilot and therefore he knows that, ultimately, nothing will be allowed to go awry. I don't have a solution to the problem other than you must clarify who is in command and if you are not happy, don't fly him.