There is literally no point in Boris or any cabinet minister going on the Piers Morgan Show.
He has no interest in interviewing them; an interview involves asking a question, challenging the answer if it needs challenging, debunking the answer with facts etc...
An interview does not involve not allowing the interviewee to answer a question posed to them before they are talked-over, hectoring the interviewee, shouting and asking whataboutery questions. This is Morgan's style.
The Government are correct to avoid the programme.