They were unable to go to Palestine because when they tried to leave it was too late. There were many Jews who made Aliyah from Germany many years before because they could see the handwriting on the wall

It is just the typical antisemitism zionists gladly boast about. They had slurs for holocaust survivors and looked down on them. They viewed the jews who dared stay in Europe with the communities they built over many years as inferior and weak. They still talk down to the diaspora today.

It is why the false equivalence of jew and zionist is so bad. It aids the antisemites in erasing the many rich and vibrant jewish communities that existed in Europe.