Its the same situation as the spirit fog, Tenzin is Tenzin and there can only be one Tenzin. Naming him after a past nomad would put so much unnecessary pressure on him on top of him thinking he HAS to be like Aang
Why didn't Aang name Tenzin Gyatso or azulon?
Wasn't Tenzin that special to him or does Tenzin have a special meaning to it?