Yeah but there’s 2 people in there, and 180 people in the rest of the plane. Isn’t the volume of air relative to the amount of people breathing it relevant as well?
The people can keep filtering a certain volume of oiled air, but at some point it's too much oil in their body.
If the people in the cockpit are incapacitated, though, it's a problem for everyone on the plane. The oil has nasty stuff that kills the pilots, but it's also hard to see through.
Basically, at the very very least, let's not dump the oil into the cockpit. Ideally let's not dump the oil into the passenger compartment either, but sheesh, let's not kill or blind the pilots as table stakes..