I assume that use of the emergency release would also be contravening bylaw 9.2.
Not if it's an emergency.
And arguably not if the barrier has rejected your valid ticket and no assistance is available. The barrier is designed to be opened in at least five ways that I know of:
1. By a ticket (including Smartcards, payment cards, NFC devices etc).
2. By staff.
3. Automatically if there's a fire almarm / evacuation signal.
4. Using the emergency release.
5. Brute force.
The barriers are designed to be opened in any of those ways. Any of those ways of opening the barrier could be "the proper manner" for the purposes of the bylaw
under the right set of circumstances, in my opinion.
Ultimately, if you have a valid ticket but (1) isn't working, you need to rely on one of the other methods. Ideally you need a member of staff to let you out, and I'm sure all TfL's operational and safety guidance is premised on the idea that assistance should be readily available to passengers in this case.
If, contrary to what should happen and to what is safe and reasonable, there's no member of staff present, arguably you should use a help point to try to find somebody, but you do need to open the barrier somehow. If you can't see a help point or it isn't working or it fails to result in anybody opening the barrier for you, you're pretty much left with the emergency release. If you're going out. If you're coming in, you're left with brute force.