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.
Like I said, Fuck the tankies.
Leftist political theory can get very complex, and when people say communism they can mean a lot of things.
Technically, Communism as per Karl Marx in the Communist Manifesto, Communism isn’t a government. Communism is a state of anarchy in which people naturally share resources and the means of production communally and provide ownership does not exist as a cultural concept. So going by the original definitions “Communist Government” is an oxymoron. Explaining what the hell happened in Russia is a whole conversation.
When people talk about communism or communist elements in a government, they are probably talking about some form of socialism.