Srila Prabhupada comments on his own possible past life as a sinless doctor.

If it is true that Srila Prabhupada said he came directly from Goloka (nothing like that is mentioned by Prabhupada on Vaniquotes), then Srila Prabhupada has said both, including he had a previous birth in this material world.

So why just except he came directly from Goloka when he also suggested he had a past life time in this material world?

There is even a book, called Bhṛgu-saṁhitā, which reveals information about one's past, present and future lives according to astrological calculations.

Srila Prabhupada comments on his own possible past life.

Srila Prabhupada - "So far I am concerned, I cannot say what I was in my previous life, but one great astrologer calculated that I was previously a physician and my life was sinless." (Letter to Tamala Krsna - Los Angeles 21 June, 1970)

Lecture on SB 2.9.1 -- Tokyo, April 20, 1972:

Srila Prabhupāda - "From Bhṛgu-saṁhitā it was ascertained that I was a big physician in my last life, very spotless character, no sins, like that.

So it may be. But actually I have no remembrance that I was a physician. So what do we know? I might have been a very big physician, influential physician, having a good practice, but where is all...? All gone.

So this situation, our contact with matter, is just like dream. Actually we are not fallen. Therefore, because we are not fallen, at any moment we can revive our Kṛṣṇa consciousness.

As soon as we understand that, "I have nothing to do with. I am simply Kṛṣṇa's servant. Eternal servant. That's all," immediately he becomes liberated.

Exactly like that: as soon as you... Sometimes we do that. When the fearful dreaming becomes too much intolerable, we break the dream. We break the dream when it becomes intolerable.

Similarly, we can break this material connection at any moment as soon as we come to the point of Kṛṣṇa conscious.

"Oh, Kṛṣṇa is my eternal master. I am His servant." That's all. This is the way.

Actually we are not fallen. There cannot be any fallen. The same example: Actually there is no tiger; it is dreaming. Similarly, our fallen condition is also dreaming. We are not fallen.

We can simply give up that illusory condition at any moment. At any moment.

So if you study all these verses very nicely, you get all this knowledge quickly". Lecture on SB 2.9.1 -- Tokyo, April 20, 1972.

As explained above, Prabhupada does mention a possible past life recorded on Vaniquotes.

However, this idea that He specially came from Goloka to write Books has no reference in Vaniquotes.

This means we are not getting direct information like the recorded lecture given above.

Therefore the discussion with Upendra and Bhavananda is just heresy, not saying it's not true, but are saying there is no clear recorded reference to prove it.

This means someone sentimentally could add their speculation to it as well.

As Srila Prabhupada suggested himself, he also could of come from a previous life in this material world to write Books directed by his Spiritual Master and Lord Krishna Chaitanya Mahaprabhu.