Well it's not totally out of nowhere.

Trump got impeached for asking Zelensky to fabricate evidence against Biden by threatening to withhold US support.

https://en.wikipedia.org/wiki/First_impeachment_of_Donald_Tr...

> The inquiry reported that Trump withheld military aid[a] and an invitation to the White House from Ukrainian president Volodymyr Zelenskyy in order to influence Ukraine to announce an investigation into Trump's political opponent Joe Biden, and to promote a discredited conspiracy theory that Ukraine– not Russia– was behind interference in the 2016 presidential election.

Yes this episode about Putin and Biden was bizarre. The world was watching how Trump was arguing for sympathy for Putin, e.g. quoting Trump: 'Putin went through a hell of a lot with me ... it was a Democrat scam ... and he had to go through that, and he did go through that'.

My interpretation is that this conversation had many layers. One of such layers was that the Trump team claimed Zelenskyy campaigned for the opposition, Kamala Harris.

And one of the objectives of this whole situation was to frame the discussion as a humiliation ritual or character destruction to show what happens when you are not aligned to deter others from doing the same in the future. Shaming individuals who are not aligned is a recurring theme in rallies. e.g.: "Do you see this? Do you want to be seen treated like this? don't campaign for our opposition".