When the FCC chair originally announced he was pursuing this (https://time.com/7318743/abc-kimmel-the-view-brendan-carr-fc...), he was pretty clear that he was doing so in pursuit of the President's directive to punish broadcast channels that say things he doesn't like. Trump himself was pretty explicit that the ultimate goal is pulling their broadcast licenses and his subordinates should fabricate an excuse.

As you say, the FCC has declined to pursue talk radio programs over this issue, even though they're clearly subject to the rule in principle. That's not a mistake, it's because those programs push viewpoints the President favors so he doesn't want to punish them.