There are discussions about this on other threads, you can seek them out.
Short rebuttal: Assuming that kabbolas mitzvos is needed and is m’akev: If there was a kabbolas mitzvos without an anan sehadi, AT THAT TIME, then EVERYONE agrees that the person is now a full fledged Ger and therefore a full fledged Jew.
You cannot be mevatel Geirus retroactively. If there was a proper Bais Din we assume that there was proper kabbolas mitzvos. Even if the Ger was deliberately fooling the rabbanim it will still be a good Geirus if he verbally was mekabel mitzvos (if they went along with it, then clearly there was no “anan sehadi”), because “d’varim sh’b’lev ainum d’varim.”
Rabbi Chaim Druckman and his Bais Din were undoubtedly a proper bais din of talmidei chachamim. Therefore, all the people they were m’gayer are full fledged Jews. Speaking askance of them will violate numerous lavim in the Torah.