I would also hit the keg with CO2 first. Since CO2 is heavier than air, that will cause a "puddle" of CO2 to form, cutting down on the O2 contamination.
I recently pulled an empty 3 gallon keg of very tasty hefe out of the kegerator to clean. When I popped the top, there was a little dab of hefe in the bottom. Since the keg was still cold, I turned it up to slurp up that tasty bit.
I got a dense face full of hefe scented CO2, inhaled, and almost blacked out.
