I don't see it as a circular argument @bhaugen
It's important to understand mutually exclusive differences within the Left. As the great American poet George Oppen put it: things explain each other, not themselves.
In this respect, I'd consider a political ideology like @ntnsndr to be outside of my zone of solidarity. A strategic ally? Sure, on a case-by-case basis.
The anarchist Margaret Killjoy created a good schematic to better understand zones of solidarity.