One of the problems for people like Trump is that they assume that others behave as badly as they themselves do. So because Trump routinely lies about things - even trivial, pointless things where it's obvious to everyone that he's lying - he assumes that everyone else does it as well.
In this case, because he's corrupt and entirely self-interested, he assumed the judges he appointed would be as well. Fortunately it seems that although some of them have some pretty far-out views, in this case at least they're taking their judicial obligations seriously, as indeed they did in refusing to countenance Trump's blatant attempt to misuse the law and the courts to overturn the election result.