Now that the series is over and we can assume that there will be nothing more, I think it is safe to think that Quirin's long letter was only to make clear how very proud he is of Varian
"Son, I am very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very proud of you.
With love dad "
Wasn't the content of the letter also qualified as a spoiler by the creators and then cruelly ignored just like Varian's mother or am I just self-frustrating my life?