I think maybe he meant to say the ""Middle ground is the enemy”" to any fascist like Donald Trump. Not that it's the enemy for everyone. You're right in that middle ground is not an enemy. Where would we ever be without some middle ground. It's just that middle ground is the enemy of the extreme voices of the present GOP, so any thought of them giving any semblance of a fair amount of middle ground is, in reality, like hoping for heaven.
It was Plato who said, “He, O men, is the wisest, who like Socrates, knows that his wisdom is in truth worth nothing”