I have a question:
Why is every Geirus in EY not considered to be for possible ulterior purposes (citizenship, marriage, etc.). It should be like the time of Shlomo Hamelech, when they did not accept Geirim at all (if anyone has a source, please inform me) due to the advantages of being a member of Klal Yisroel.
However, once it is done, the problem is easily solved by allowing secular marriage.
Also, is the question if they ever accepted “Ol Mitzvos” or if they backtracked? If they never accepted Mitzvos then the Geirus in not invalidated retro-actively, it was never valid in the first place.