If United had got 9 more points from home games against Bournemouth, West Ham, Everton and Wolves, they would be 4th and Amorim still in a job. Without 'bonus' wins against Liverpool, Chelsea and Newcastle, they would be 17th.
I think he should go, but there is an argument that United are on par points-wise for European qualification. Can get to 66 points without any points from games against the top 5. It will be the points dropped to Brentford, Palace, Bournemouth etc that will cost him.