Just throwing it out there... if the radio is a problem, I'd love for Paul and friends to replace both the radio and avalanche source with an "infinite noise multiplier", which I feel is more secure than either alone, but probably not as secure as these two very different sources together. However, that would delay things quite a bit. I'm hoping maybe version 2. Also, the wider community has zero experience with INMs, so it will take a while before such a source is generally accepted.
Also, this concern about the radio requires someone to 1) hack the TRNG, and 2) have a nearby receiver. At that point, they probably could more easily just PWN your system, and forget about the TRNG. Paul is doing some clever things to make it very hard to hack his firmware, but a keyboard logger is still easy for an attacker with physical access, as is any number of attacks.
I don't care how trustworthy everyone involved is or how closely we all look at it.
"Shouldn't an HW RNG NOT have any secondary communication method built in?"
Yes, that would indeed be a best practice.
Seriously. A radio. And not just any radio, but a software programmable, general purpose 802.x radio with a published spec, etc.