That’s like saying if my house is protected by a passcode lock, the cops can just break down my door and walk in. Sure, they can, but there are clear rules of when they can enter and search my property without my consent. So, sure, they can enter my phone, but that doesn’t mean they have the right to in the first place.
The comment you’re replying to specifically discusses Fifth Amendment rights. The police would not generally be violating those rights by entering your house without a warrant. That would be a Fourth Amendment issue.
(One might argue that breaking your door without due process of law would be a Fifth Amendment violation. I have no idea what existing precedent says about that.)
