Some of it. There is still the ultrasonic channel: beacons are emitted by various tv's, stores, etc. which can be used to capture location and other data and exfiltrate from the phone with the right software running. And of course the regular microphone can capture conversations and media.
If the bag is not opaque, there is still an optical channel.
Plus there are still accelerometers and magnetometers which can do rough inertial and geo location estimation.
The bag may help with some exfiltration routes, but it can store locations and other info and upload it when it gets a signal back.
