As to what the OmniCause is I'd say educate yourself by doing the work (two more oft-heard phrases uttered by those who are into the OmniCause), e.g. by reading this WSJ article:

The ‘Omnicause’ Is Collapsing - Queers for Palestine? The contradictions are causing a crash at the intersection.

https://www.wsj.com/opinion/the-omnicause-is-collapsing-prot... (https://archive.ph/m5GVm)

...or this one:

omnicause

IPA: US: /ˌɑm.niˈkɔz/; UK: /ˌɒm.niˈkɔːz/ Noun

    Political Neologism (Intersectional Activism): The intersectional relatedness of multiple major political causes and issues, often used to describe the expectation that a "good progressive" must support all such causes simultaneously as a single "package deal". It is frequently used critically to suggest these links are false, exaggerated, or counterproductive.