If their wireless is off, they really shouldn't be able to receive messages. Some of his "rulings" don't make much common sense while others do. In order to have a presence in the matrix, a device should have to be findable on the matrix to receive the message, hence require an icon. The same kind of goes for something like a jammer not affecting comlinks, which is something in my table top game doesn't apply. Granted, that decision came after more experience with the system, and when we started, sr5 was still fairly new.
As for the background noise, I kind of ignore that for any non-matrix actions. Going one step beyond your example, a fair portion of the populations cyber eyes would go offline in a commercial district, preventing them from seeing any of the advertisements that are creating the noise in the first place...
So, if this works, background noise affects matrix actions, jammers affect everything (including communications). Yes, you need to be wirelessly active to send and receive communications. The only exception would be if you get so far out you honestly need something like an uplink (which some of you have anyway). Does this work for everyone?Also, of course, since you never specified, you might be sitting right next to Ultra hiding, and the point about receiving wireless would be moot anyway.
I suggest all getting datajacks and setting up a wired network between yourselves at all times just to be sure
That would be the most elegant solution.