Yep, your interesting input doesn't need bold letter
Back to initial what-if, USA was in a "moral" and cold (support, supplies etc) war against Germany from the start.
It is unthinkable USA could trade UK for Germany, it's not only about diplomatics, FDR was guided by moral and ethics. He would never have made such a smelly bargain like the Germano-Sovietic pact was.
Here are some parts of his neutrality speech at the outbreak of WWII :
"My countrymen and my friends, tonight my single duty is to speak to the whole of America. Until 4.30 o'clock this morning I had hoped against hope that some miracle would prevent a devastating war in Europe and bring to an end the invasion of Poland by Germany. (...)
It is right to point out that the unfortunate events of recent years have, without question, been based on the use of force or the threat of force.
(...)
You must master at the outset a simple but unalterable fact... When peace has been broken anywhere the peace of all countries everywhere is in danger. It is easy for you and for me to shrug our shoulders and say that conflicts taking place thousands of miles from the continent of the US and indeed thousands of miles from the whole American hemisphere do not seriously affect the Americas and that all the United States had to do is ignore them and go about its own business.
Passionately though we may desire detachment we are forced to realise that every word that come through the air, every ship that sails the sea, every battle that is fought, does affect the American future.
Let no man or woman thoughtlessly or falsely talk of America sending its armies to European fields. At this moment there is being prepared a proclamation of American neutrality...
This nation will remain a neutral nation. But I cannot ask that every American remain neutral in thought as well.
Even a neutral has a right to take account of facts. Even a neutral cannot be asked to close his mind or close his conscience. I have said not once, but many times that I have seen war and that I hate war.
(...)"