In one exalted interpretation, knowledge is compared to water. Now, water is essential for survival of all life on Earth. Hence, as water must be freely available to everyone, so must knowledge. Clearly, the ones who deny water are the cursed ones here on Earth as well as in the afterlife and shall burn in its hottest parts.
Further, S. Qadi Noman says, when interpreting the Qur'an Surah Al-An'am verse 120 ("Forsake open and secret sins .."), that the only way to avoid secret sins (the Qur'anic word used in this verse is "batin") is to learn the knowledge of batin, i.e. the underlying meanings and not just the outward forms. Hence, when someone denies knowledge and hides it he is making it impossible to avoid the "secret sins" mentioned in this verse. Hence, again, they are bound for hell fire and perdition.
Moreover, the Qur'an was revealed to the Prophet for all Mankind and not for some minor and tiny community in India! Hence, the Qur'an and its message is universal, in fact, its message is independent of specific religious affiliations. In this truly exalted sense, the meaning of the word "mumin" includes all Mankind. All 7 billion of them. Hence, the true representatives of the Prophet and his universal message, preach to everyone. The great Sufis who came and settled in India converted millions of people to Islam as they understood this universal message and preached openly and freely, giving water to everyone and not denying it to anyone.
Also, during the time of the Fatimid Imams there was no compulsion for their subjects to adopt Ismaili doctrines. The series of lectures which S. Mu'ayyad delivered were hence open to everyone and there was no need for secrecy. Secrecy was only adopted during times of persecution. Clearly, if one runs an empire it is hard to maintain that one is being persecuted!
(Incidentally, S. Mu'ayyad himself says in one of his lectures that Allah addresses Mankind in general, and has appointed "arabab-e-taw'il" to explain the points that can't be easily understood by oneself. Hence, clearly, even Mu'ayyad himself understood the universal need for such teaching.)
However, those who live like a frog at the bottom of a deep, dried up and slimy well think their muddy waters and darksome holes are the universe, never realizing that a vast universe of sunlight exists outside their well. Such are these fanatical mullahs who have emerged in recent years in this organization corrupted by Iblisi pride and hubris.
Incidentally, one can't actually take things like "so-and-so is secret" at face value. For example, SMB once said that the Kanz al-walad is so secret that only one da'i can teach it to his successor. However, if one looks at the manuscript record one finds that this book was copied many, many times (and by implication, studied in depth) by non-da'is too. For example, STS taught it to SMB, SKQ and his raas al-hudud. So clearly this book was not as "secret" as one makes it out to be.
Finally, this is no longer the era of secrecy. Given centuries have passed since the writing of most books on taw'il and haqqaiq the purpose of secrecy, practiced during the time of persecution, is no longer of relevance.
Now my last point: the interesting thing is that a rabid dog hates water. The analogy is obvious to those who understand, and hints are enough to know those indicated. No need to name names.