That may be so but Palestine was already the designated place of Zionism while he was still alive and actively growing his Zionist movement. There were other (non-political) Zionist groups actively buying land in Palestine and helping to fund groups of Jews to set up agriculture-based homesteads. Herzl met with these groups to try to bring the Zionist efforts together. The aim was never to take land that wasn't Jewish-owned, but in the establishment of new nations, it never works out that way.