[karaterobot]

The thing (many) people are worried about is that, having instituted a backdoor on the user's device, Apple may lose the ability to control how it is used. In the past, their strongest defense when the FBI asked them to use a backdoor to decrypt a user's device password has been "we don't have a backdoor that allows us to decrypt a user's device password, so we couldn't do that for you even if we wanted to".

From now on, when asked to check whether a user's encrypted phone contains arbitrary content the FBI wants to know about, Apple can no longer say "we don't have a way to do that." Sooner or later, you can bet they will start doing it, whether they want to or not.