I think Manchin and Sinema figured they’d have to become Pubs if they voted to acquit, or the Dem Party would dump ‘em. Since Trump was in no danger of being removed, they could vote to acquit, and in 4 years, who remembers? Not many, and probably none who would vote for them anyway.
Jones is toast unless the Pub candidate makes a major stumble.
Manchin also wants to run for President on the Rat ticket. He can’t do that and vote to acquit.