No, he should go out there with something that causes local interference in the frequency that thing uses :-)
Good point. I did a little research, and by no means is this conclusive, but I found very tiny hearing aids that fit largely in the ear canal and thus are called “invisible” but none that I found supported wireless streaming. However that is commonly available in hearing aids costing just a couple thousand bucks, and for the right price you might be able to get both in one, especially if it only had to work for an hour or so.
The streaming types naturally support Bluetooth so you can hear phone calls and music, TV, etc through them. So if someone were to use such a device they’d probably just use an iPhone or similar device for the transmitter, and it would have to be quite close by, as the range spec of “up to 100 meters” is going to be drastically reduced in an enclosed space. Point is, while it could work the signal would be on the weak side and very easy to “jam” with a broadband 2.4 GHz jammer. Bluetooth is a little more robust than wi-fi because it frequency hops among 79 channels but still can be jammed, and the most powerful jammers happen to be owned by the federal government ;-)
WASHINGTON DC - Protesters walking in the direction of the White House— FJ News Reporter (@FJNewsReporter) September 24, 2020