Not cooperating is legal, unlike not paying taxes. He could just remain silent and request a lawyer.
LE can and will lie to you, and make invalid threats in order to get people to confess or just slip up so they can pin something on them. There's no incentive for LE to behave ethically or nicely; they don't get penalized for lying.
> Not cooperating is legal, unlike not paying taxes
Right. I was just highlighting the similarity between those two things: if you disobey "authorities", something bad will happen to you. Here it's good to notice that extortion is illegal unless it's called "taxation", in which case, attempting to avoid extortion is illegal.
LE can and will lie to you, and make invalid threats in order to get people to confess or just slip up so they can pin something on them. There's no incentive for LE to behave ethically or nicely; they don't get penalized for lying.