Cant really say either way.
Fwiw if he did change passcode when he moved phone and hasn’t used it in over 2 years I could accept he thinks he knows possible combinations but can’t be certain on the exact one as a genuine thing, although I can’t be sure.
For me this problem addresses a greater issue which is IF government ministers are going to communicate about operations via web messenger apps then they need to be provided with a secure & encrypted service using private secret service protected UK owned servers.
There should be an official policy that all discussions on whatsapp or other 3rd encrypted services are not allowed for government business.
It’s well known MPs have lots of whatsapp chats, maybe it’s time that if these chats are going to be observed in official enquiries then it should be a clear boundary between what is personal chat & what is government business & have appropriate tools for each one.