¶ PABST OLDSTYLE OPEN was never released in hot metal type. It remained as an incomplete alphabet until the digital era.
Possibly Goudy had never even seen this interpretation of Pabst Oldstyle. Or perhaps it was the work of the engineering department but met with Goudy's strong disapproval.
So all is a matter for speculation.
At least I have never read any record of it. Several characters for the name of a company was cut in this face for a private use.
Frederic Goudy's had never mentioned this type face in any of his writings.