You are correct that 4-B was an earlier mention than the listing in the Price list but the date on 4-B is January 22, 1952 or well after the 1952 model year got started. Also, going back earlier than that, the Confidential Bulletin that announced the 1952 Kaiser Virginian models (released in December 1951) lists it as a factory installed option on 1952 Kaiser Virginians.
The bulletin itself states that it is a retrofit item for 1951 Kaisers as well (and will fit just as it should on those cars). You will find Bulletin 4-B among the items in the KFOCI HANDBOOK VERSION 4.0 section on 1951-1952 Kaiser Virginian accessories (one of the last pages in the .pdf file).
Also, if you check the back side of the KFOCI JUDGING SHEET, you will find a deduction spot for "Miscellaneous Non K-F & Incorrect Components". According to the Fred Walker judging "schools" in 1975, 1976 and 1980 (that I attended), Incorrect Components includes Kaiser-Frazer factory accessories NOT made available to dealers during the model year the car was built. Again, this kind of thing is a point to be addressed during the work up of the written judging standards.