So he knew that it was plagiarized yesterday but they were going around yesterday saying that she didn't plagiarizer anything.
Either they were lying or this is a bullshit explanation.
Nothing they did yesterday showed that they were offered this resignation.
Of course this is a lie.
We already have multiple sources leaking to the New York Times about what happened.
Trump was told that he should just fire somebody, so he found somebody and fired them. It's a lazy, completely unconvincing coverup.