All he did there was fail to believe that Putin would actually do something quite that extremely terrible. (Not my assumption. Later tweets supplied that.)
He was accusing Biden and the media of probably crying wolf.
He expressed a perfectly valid and supported-by-evidense opinion that the media stokes fires and the US manipulates the people via the media, and therefor you shouldn't just accept everything without question.
The media and the US government do in fact both do those things. You in fact should not just accept everything without question. That is all true and was true on that day too, because it's true at all times every day.
Merely in that case, that specific claim by Biden and the media was not false.
And because he got that wrong, he stopped tweeting at all because he considered his opinions and advice of low value on that subject. What lack of integrity!
Try again.