So let me break it down further. The ISP isn't allowed to sell E2EE apps because it would violate its lawful intercept requirement to not encrypt the data it gives to the government. Your E2EE apps have to come from a different company. That's why SMS isn't E2EE.
Are you seriously just trying to be this obtuse? WTF said anything about the ISP selling anything? You use Signal? You use PGP? Who uses anything from an ISP other than their bandwidth? I've never even heard of an ISP having an app let alone selling it that end users would use. Like it must be painful to think up nonsense like this. It'll be a lot less painful if you just think about it like a normal person using apps instead of whatever it is you have in your head. Damn near troll like