Fuel pump rod - what is the purpose of umbrella?

[Ziggster]

I need to replace the fuel pump rod and bushing according to my machinist due to wear as he has started the ré build (C69). I understand there are two different lengths depending on whether the intake is aluminum or steel, but what purpose does the "umbrella" serve? I'm assuming it diverts oil from splashing upwards, but he said it helps to "pump" air as part of the crankcase ventilation system which I still haven't fully grasped?