It isn’t meant to directly compare this to witch hunting. It’s a case of people overlooking brutality because witches are bad anyway right? There are zillions of examples of this. It’s the concept that’s important. Saying that the technique of lying is ok because it gets rid or murderers is wrong especially in light of the fact that there are other ways to do it.
And yes, there is a grey area where interrogators don’t outright lie but are still highly deceptive. I don’t care about the grey area, I just care that police are allowed to outright lie. That is not grey. The example that I illustrated reveals how sinister the police can be. It is more emotionally stirring than mechanical lying. But the interrogator did reveal her title and so whatever. Seriously twisted still. But making outright lying routine is wrong. I don’t want to live in a world where police tell flat out lies to people. That is why we have Miranda rights. Under your logic there should be no reading of Miranda rights, allowing the police to tell the suspect literally anything like “if you don’t confess we will do x” or “you have to tell us something or you’ll be locked up forever” or whatever. Miranda rights exist for an extremely good reason. And stopping outright lying is a continuation of the spirit of Miranda rights.