Hi @connorohess,
You should be able to find “Marketing contact status” like any other contact property 
No need to create an additional segment. The key to finding this in workflows is to select “When filter criteria is met” in the enrollment criteria, not the event-based filters.
It sounds like you’re trying to set marketing contact status like any other property via “Edit record”, it is however a dedicated workflow action “Set marketing contact status”: Set contacts as marketing
Best regards