This is a lie because it is an attempt to deceive Emma. Hook is hiding something. He may not be deceiving Emma through speaking, but he is deceiving her by not speaking.
Also, there is a huge difference between Regina and Hooks’ behavior. As others have said, Regina has done the right thing many many times this season when she could have done the wrong thing. Hook is still being the same. Drunk, lying, thinking only of himself, no care for anyone but keeping Emma, right up til the end of the episode. He tried to destroy his memories. He was going to leave without saying anything. He was drunk when he talked to Snow and still didn’t tell her anything of what happened and that maybe she shouldn’t be happy about their engagement. Hook was still the same. There was no change.
There was no repeatedly trying and doing the right thing like with Regina. Hook might do one helpful thing, maybe, he also might not. Hook might just come back and Emma will hug him and that will be it. We don’t know, but even if he does one helpful thing, it won’t prove that he actually changed because he got caught. He has yet to do the right thing because he wants to be open and honest with Emma. He needs to do the right thing because it is the right thing and not because Emma might be upset and not because he got caught or Henry might tell or any of that.