I agree that these arguments are based entirely on speculation, and there are diminishing returns.

Yet casting Churchill as the white knight holding firm against the rising tide of evil is also not helpful. For all his sins against the people of the colonies, I do not believe Churchill was a malicious person. He was a product of his time, and in some respects held to outmoded ideas even for his contemporaries. I'm not interested in holding Churchill or any historic figure to modern standards of morality, but it is helpful to think of him as more than just the bulwark against the Nazis. He could be both great for the UK & still a net loss if we're considering "human suffering".

I will say that using the nebulous metric of "human suffering" is an incredibly slippery slope for evaluating the actions of any historic figure. For example, some sources (eg, Shashi Tharoor in the top level comment) put the death toll from negligence just in India in 1943-44 during Churchill's tenure at over 3 million. Some like Gideon Polya put that number at 7 million. Contrast with the 6 million Jewish lives lost in the entirety of the Holocaust. Even if we accept the much more conservative figure of 2.1 million lives lost just in the single Bengal province, that's comparable to the 2.7 million killed in all the extermination camps put together. Yes, it was a complex situation, and Churchill's tenure was just the culmination of British destitution of what was once the most prosperous part of the world. I don't hold Churchill personally responsible, but many do, at least for some part of the deaths and immeasurably more human suffering that could have been avoided for little strategic gain.

If Churchill was critical of the caste system, he did precious little to address it. Indeed, the caste system as it exists today was largely a British creation. They stratified a relatively fluid social organization (jati), gave it legal sanction under the guise of a practically obscure text (manu smriti), and applied the status of "varna" upon it. This is not to say Indian society was perfect or that the caste system wasn't oppressive, far from it. But to state that Churchill's bigotry should be seen in the light of his disdain for caste is really stretching it. Indeed, if Churchill was so critical of caste, he had no qualms about his seeing White Protestants at the top of a Darwinian caste system, above Indians, who are themselves above the more savage Africans. Yes, he was a product of his time, but even his contemporaries saw him as extreme in his racial views. In light of his racial views, it's hard not to read that into his willingness to sacrifice millions of Indian lives for minimal gains on the European theatre (the grain supplies eventually ended up not with British soldiers, but shoring up Eastern European stocks just in case). Does an Indian life not equal a European one?

The quotes I believe largely come from the private diaries of Leo Avery, the Secretary of State for India in Churchill's cabinet, and his lifelong friend and ally. Leo Avery shared Churchill's disapproval of German appeasement, yet noted that in his disdain for the plight of India Churchill was "not that different from Hitler".