I would be terrified of using a bluetooth mesh network in a situation where private, encrypted communications are illegal. That would be literally walking around transmitting your intent. It’s a great idea in a free country though.

You have a point but that would means that the only other solution is to fall back to personal comunications, every electronic channel is unusable in such situation.

In a dystopia, you want to blend in.

Or you can simply have so much irrelevant data that the few important bits are lost in a sea of randomness if you don't know where to look.

Something like deltachat has the right idea there - you have to look like boring email on the network. Maybe even layer on stenography -sending boring emails with cat pictures, but your messages are hidden inside them.

The main point of using bluetooth is to not rely on a centralized server that can be compromised and/or shut down.
If you still use email as transportation layer you could just write an app that really has e2ee, plausible deniability or any other feature you want since in the end you are relying on the same centralized infrastructure.

Honestly, I would probably go with sneakernet. A microsd card can be hidden very easily, are difficult to detect electronically, transport virtually unlimited text, and be encrypted in-case the mule gets caught to prevent networks being exposed. The latency is just a necessary evil.

The latency is not the problem, it is already known that to move large quantities of data the fastest method is to send an hard drive (or whatever else).
The real problem here is where the mule can go.