Many people in the US, especially those in Hollywood, were against the US supporting Great Britain and the other Allies until 22 June 1941. For some strange reason, their attitude changed that day although I don't recall if they publicly stated why.
Could it be that they didn't want a lot of young Americans dying in yet another European war that didn't need to involve the US?
The protests were about Lend-Lease and such, the US was not declared actively engaged until Germany declared war on the United States. But why did the protests and such end on the 22nd June 1941, and not on the 7th, 8th, 9th, or the 10th of December 1941?
Yes. I do understand your reasoning. Yet, there is an element of hindsight in it. At least in my humble opinion.
The reasons why people do things can be complicated. Or silly. Or even simple. And the simple reason might indeed be that they were Soviet friendly instead of UK friendly. I think it is more complicated than that. I think most of them were simply US friendly. That they thought it was a silly war they could stay out of. I suspect it was a gradual change from the fall of France to the fall of Greece. But much of that was, I suspect, mere background noise. California, is after all, a really, really, long way from Europe. Why would they bother with what happened over there? No TV to see the suffering of the innocents. But when the silly moustached guy declared war on USSR it went from a conflict over Danzig to a threat to the world as they knew it. Then they realized that the German leader and his cronies were a threat to the world. IF USSR would fall, what could then stop him?
Sweden have gotten some flak during the years for we traded with Germany. Lend-Lease is getting a lot more involved than trading. Yes, I know other stuff happened as well. What I am trying to say is that I think many saw the Lend-Lease as a way for US to get involved in a war they thought US should stay out of.
Have a bit more patience with newbies. Of course some of them act dumb -- they're often students, for heaven's sake. - Terry Pratchett