It's entirely possible that the engineering crew took into account the air blast from the fan and/or the forward motion of the vehicle that would blow any drainage back toward the firewall. That deflector probably came into play when the vehicle wasn't running, or moving down the road. Early valve covers had ventilating slots in them, and water dripping onto the engine could end up in the oil pan.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!