Onebigmonkey has posted an excellent analysis of this 'claim' - https://onebigmonkey.com/itburns/bartbs/bartsbull.html
Onbigmonkey certainly has done a great analysis. A fair way down, he says this:
Yes, von Braun went to Antarctica. Yes, he collected some meteorites. But see if you can guess how they know now that they are lunar in origin.
I have done a fair bit of study of von Braun's trip to Antarctica, but I can't find here in New Zealand the same sort of stuff that would be available in the U.S., so I have never seen anything about him collecting meteorites of any type while there. As far as I can tell, he never went anywhere near the areas where lunar meteorites were later found.
Does anyone know anything about von Braun collect any meteorites in Antarctica and, if so, what information is available?