It's not being righteous, it's looking at the facts.
Theresa May was the worst Home Secretary in history. She made numerous poor decisions that has resulted in a severely damaged police service which is not coping. This was despite her being advised and warned about the consequences of her actions. Virtually everything she was warned about has happened.
The point I was making was that the old codger viewed Theresa May as a successful Home Secretary. She wasn't, she was terrible, the Police, Windrush, Border Force, the list goes on and on. Theresa May is a complete failure in all walks of life. Therefore, the old codger has severely flawed judgement, which is proven by her views on Theresa May. That flawed judgement then calls into question whether the old codger's view that Brexit is a desirable proposition, is a good one. That's all, nothing righteous in that. (Try saying my statement is racist or Islamophobic, that seems to be the current fashionable technique to close down discussion.)