The parent poster was claiming that the story around Trump has died, seemingly suggesting that high profile figures on the Democrat side have realised it doesn't pay to keep pushing a story that now makes their own guy look bad. Personally I'm not convinced, most stories tend to fall out of the spotlight sooner or later unless new discoveries are made that can keep them interesting. Plus it's premature to suggest we've heard the end of that story anyway.
I think it’s because of (c) I.e., everything worth reporting has been reported, the ball is in the justice department’s court to decide what to do about both Biden and Trump. Merrick Garland is a methodical guy so it’s wait-n-watch wrt to the classified docs story.