I'm still not clear on what this formation is, or how it's at all similar to what we were running other than the fact that you're playing the four center backs at the back. Richarlison was never in midfield for that setup, so I don't understand what you're proposing that you say Ancelotti missed as an option.
It seems like a relative risks problem to me. The risk with bringing Gbamin on is that he plays poorly due to the long absence. The risk with bringing King on and changing the formation is shipping a goal during the adjustment under heavy pressure from Palace. The latter sounds to me like the type of risk that van Gaal might run, but never Ancelotti.
Why do you want to bring King on? I don't see how going three at the top was going to get an insurance goal with Rodriguez off and DCL misfiring. If the Coleman sub was the error, shouldn't Ancelotti just replace Rodriguez with Gbamin, leave Godfrey on the bench and forego the third sub? Or are you saying that one of DCL/Richarlison should have made way?