Incorrect, if they want access to your encrypted information they may get a warrant, you can then defend yourself against said warrant by contesting it, a judge might hold you in contempt for not giving up the keys (that is a contempt to try and make you comply not a punitive one so is only supposed to be until they figure out your not going to). This is not what they seem to be worried about.
They are worried about not being able to just take or use secret courts to access whatever they want. Pervasive encryption means they can no longer get all the info they want from the middle men who tend not to fight back much, use national security letters when even the secret courts wont give them a warrant. Having to use actual warrants served to the people effected who might fight them and use the media to shame them means they better have a good reason vs just fishing. You can also devise hardware and protocols that put a time limit on being able to decypt things that would limit the time held in contempt (simple one is a chip that holds the keys and erases them if it does not get a passcode every so often or looses power a basic extension on existing TMP).
In short you can have secure encryption that the government could force you to let them access. It's messy, time consuming, and does not always work.