It's impossible for the ref to win...
We want them to be consistent & apply the laws of the game to the letter yet also simultaneously being empathetic, apply common sense or just plain ignore them when it suits.
Yes, other players began to run on the pitch, by rights he could book them all, but he also has to think about managing the game & the situation. The ref glared at them & they thought better of it & retreated. Palmer did not. Unless we're saying we want Dasilva banned too I'm not sure what we're campaigning for here?
I think the ref handled the situation perfectly, understood the emotion & gravitas of the situation & cut them a little leeway & I'm sure his assessor will cut him some slack for that too.
A substituted player sprinting the entire width of the pitch for a knee slide in front of the fans is very different though & had he not booked him he'd be getting at least a stern word himself from the assessor.
I would have done the exact same if I was refereeing tbh.