There's nothing insane about the "shove it in Park" advice, at 35 mph there's no chance that it will actually engage the pawl and the vibration will likely free a stuck governor. (nothing to do with "backflow", just simple vibration)

It's possible that the problem isn't a stuck governor but might be a governor that has tossed its guts into the tailhousing...this often happens when the "E" clip holding the cross shaft comes off.