I really have no basis for evaluating the matter at hand one way or the other, but I would like to point out that Khrushchev is not a great source, especially when he's saying "Here's something Stalin said all the time in private that he never said publicly".
Don't get me wrong, you may very well be right, but I find it less convincing when paired with this evidence than if the claim is simply made with no evidence at all.
It took me a second to get what your saying, it's kind of an obtuse argument, but no, that's not the logical implication of what our friend said. The logical implication is that the Lend Lease program was a way for the US to tip the scales with minimal cost to American lives, essentially having the Soviets fight a proxy war (insofar as Lend Lease was the basis for their being able to fight, something which I need to assume gets exaggerated by anticommunists for obvious reasons). The US could have instead spent the same resources on its own military to further enable it to fight on the western front rather than put it in Soviet hands.
I don't think it's really that interesting or useful an argument to make, but it does make sense.