Nonsense. The person who controls whether or not they get to return to the Church obviously has considerable leverage, unless they don't give a damn (so to speak) whether or not they get back in. The latter is clearly not the case, or else Williamson would be responding to the interview questions with the verbal equivalent of an upraised middle finger rather than with Clintonesque parsing.
Regardless of what you think, it is neither a heresy nor a sin not to believe that x number of people died at Auschwitz or wherever. It is CRAZY and it is obviously an attempt to minimize the impact of the Holocaust, just the way the ravages of Stalin have been minimized to the point of nearly disappearing from history books.
Williamson is also a 9/11 “truther” and appears to have nothing but contempt for the US.
But he can still be a Catholic. As far as his public role, obviously, the Pope will prevent him from exercising it and will probably require him to go into seclusion.
I notice none of the wrath of folks like you when our very own President of Hope and Change “rehabilitated” and gave the US seal of respect to a Holocaust denier who hosted a conference of Holocaust deniers and in fact everyday publicly proclaims his desire to kill Jews: Ahmadinejad. And he’s somebody who really hates Jews, really would kill them if he had a chance, and is not about to come under the control of anyone who can change his mind.