"As Mr Trump’s opponents called this a disaster, his supporters lambasted their criticism as hysterical—wasn’t everybody saying a year ago that it was sinister to have so many generals in the cabinet?" What does it mean by "wasn’t everybody saying"?
If you want to get to the meaning of a phrase using a contraction, break down the contraction first.
In this case, it would be 'was not'.
Therefore, 'was not everybody saying'
The writer is simply bringing up that many people were "saying a year ago that it was sinister to have so many generals in the cabinet?"
He is saying it in a provocative way in order to allow the other side to see his point.