Fascism is a political ideology and system (sort of) that requires a whole lot of people to keep it in place. A "lone President" assassinating his political rivals in a single act is just a regular old dictator move. No fascism required.
Since the prevailing view of Trump and MAGA Republicans is that they are fascist, it's not a stretch to point out that the proposal in the parent comment is far closer to "actual" fascism than the actions of an incompetent enabler.