Why only Germany?

Going through some scans of Automobil Revue, I have now found evidence that the decision to allow German cars to be raced as long as the entrant was not German was taken at the February 1946 meeting. Therefore my conjecture re Alice Caracciola and Indianapolis was correct.

It also seems that in early 1946 there was nothing to stop the Swiss issuing Caracciola an International racing licence, since the issue of drivers was not dealt with until June 1946, at which point the decision on cars was reiterated.

In October 1946, the CSI rejected specific requests from both Caracciola and Stuck to be granted International licences, citing their June decision as the reason.

So, some gaps filled, although no closer to an answer to the Stuck question.