There are secondary contact methods, these weren't activated.
There was no emergency call activated.
Im not an aeronautical engineer, but I guess neither are you. The author (who is a pilot at least) claims that the right procedure in this case would be to pull
all "busses" (fuses I assume), which in all likelyhood would disable any and all contact methods. Unless some of them arent fused, which seems unlikely.
Anyway, not saying his explanation is the truth, I have no idea, but it does sound like a workable hypothesis, even though it doesnt seem to rhyme with all the facts either.