He was a little fidgety and maybe not sitting quite the way others were
I'm assuming "he" was Trump.
Trump walked by Jimmy Carter, the Clintons and the Obama's and shook no one's hand.
Not until he sat down. It was Obama, who Trump accused of not being legitimate that reached out and shook his hand. It was Mrs. Obama, who right wing scumballs call a man even though she has two daughters and who Trump accused of running wild with tax payer money who then reached out and shook his hand. Clinton shook Melania's hand but just couldn't bring himself to shake Trump's hand.
So Trump is sitting there under all kinds of investigations being humiliated in front of the world. Clearly, Trump was very upset and wanted to be anywhere else.