I think the intended image there is that they can come and go without announcing themselves, which is what's being proposed.

They can still access your E2E encrypted messages under existing laws by bringing a warrant to your door and asking you to hand over your phone, then:

A: finding it unlocked. B: hacking it. C: using normal police techniques to convince you to hand over the passphrase. D: using a key disclosure law to compel you to hand over the passphrase.

What they want to do instead is take the warrant to Facebook/Signal/etc. and get them to hand the messages over without needing to interact with you at all.