Rav Eisenstein shlita was was Rav Elyashiv ztl’s talmid muvak and gabbai for many years. Very few other people can speak as authoritatively on Rav Elyashiv’s positions as Rav Eisenstein. Especially on an issue such as this where he spoke to Rav Elyashiv directly and is relating what he stated.
Rav Reuven Feinstein shlita also supported the EJF and was the chairman of its halachic committee.