Qwert, a large number of east side families send their kids to my yeshiva. None of them have televisions at home. Like any neighborhood, the east side has modern people, and yeshivish people. The advantage of that particular community is that the modern people have more of a connection with Torah jews, because that’s the kind of rabbonim who are in the area.
If you are wondering why rav dovid didn’t sign the kol koreh, i believe the answer is that he was exceedingly humble and might not have thought he belonged on the list.
My rebbe, rav belsky, was a prominent posek at the time of that kol koreh, but his name isn’t on there either. Yet he spoke about the evils of TV in yeshiva numerous times, and wrote a powerful haskama to a sefer about the prohibition of having/watching television, where he says “all of the gedolim of the previous generation screamed like cranes about televisions because of the great danger…”
Why didn’t rav belsky sign that particular kol koreh? Who knows. Maybe for the same reason as rav dovid. Why don’t you ask rav dovids son why he didn’t sign it, or what his shitah is, instead of assuming things? Only if you’re ready to accept the psak that is