Yeah this is utterly unrelated to the immaculate conception. This is just a really, really weird way to bash Bishop Fellay for being on a side of the invincible ignorance debate that OP disagrees with. Doesn't Bishop Williamson hold this too? Archbishop Lefebvre did as well.
It has everything to do with the Immaculate Conception because here you have a Hindu who Bp. Fellay claims is either born in a state of sanctifying grace or has put himself in a state of sanctifying grace. What he is actually teaching is teaching salvation by implicit faith, which is what Abp. L, and all who went to his seminaries believe and teach today, that Mohamedans, Hindus, Buddhist, Jews, indeed people in all religions can be saved by their belief in a God that rewards, that they can be saved despite not being baptized, not desiring to be baptized, not desiring to be a Catholic, not believing in the Incarnation or the Holy Trinity, and even despising the Catholic Church, AND not being "invincible ignorant". They call it implicit faith because they say that the religion that the person practices shows implicitly that he believes in Christ and the Holy Trinity. This implicit faith trumps all of the dogmas on EENS and thus the person can put himself in a state of grace.
There is not saint that ever taught such a thing, but it is what 99% of people who defend baptism of desire believe, like yourself for example. Don't you believe that?