Justin Mohn, a 32-year-old Pennsylvania man, is in police custody after allegedly murdering and decapitating his father, claiming the latter was a “federal employee” and a “traitor.” Before his arrest, Mohn posted a 14-minute video to YouTube in which he displayed his father’s severed head, proclaiming: "This is the head of Mike Mohn, a federal
I’m not familiar with the British Monarchy so I can’t really comment on how appropriate your framing is.
What I can point out is that your statement is logically inconsistent on its face.
One can’t be neutral towards a fascist state because the fascist state won’t allow one neutral. In such a condition, anyone who claims to be neither for fascism or actively anti-fascism is pro-fascism because the condition of fascist power will direct all the labour and efforts of participants to the support of the fascist state. In such a condition, pro-fascist is the default condition, and anti-fascism can only be achieved through conscious effort and educated and effective praxis. There is no neutrality. One is not neutral in the face of fascism simply because one declares to be so.
So, if the same conditions essential to fascism are true of the British Monarchy, then the nature of the political situation is stopping Brits from being neither for or against Monarchy. If your assumption that fascism is like the British Monarchy is true, then one could only be pro-monarchy, or achieve anti-monarchy through conscious and intentional effort.
You are not making any distinction between those who would want a fascist state to endure and those who would be indifferent to replacing it with something else. But I think that distinction gets to the heart of the question.
You are also assuming that fascists and anti-fascists are only concerned about their own condition. Suppose you asked an American their opinion of Mussolini and they responded “He was terrible”. That’s clearly anti-fascist. But what if they responded “Never heard of him”? That’s neither pro or anti fascist, yet the neutral response won’t advance a fascist regime.