There is no way any rav, considered mainstream chariedi, will sign such a hetter.
Have you heard of ANY of these "Rabbis" before?
None of Chacham Ovadia Yosef's children signed, no one from the Moetzes Chachmei Hatorah, not even from the Chavrei Moetzes Harabanut Harashit L'Yisrael!!!!!!!
You need "shoulders" to start with hetterim like this, its not for the Ram in some Yeshiva to sign on, or the Mara Dasra of some small Yishuv, or the Rav of a Beit Knessset.