When transferring inventory to another org, the date is grayed out. The date the transfer is accepted becomes the date the items are removed from/on reports. Often a location will transfer an item but the person responsible for accepting the inventory at the other location may be out for a few days. This causes issues across months when 1 location needs the item to be removed from their inventory balances on 11/30, but it wasn't accepted until 12/02.
The customer needs the transfer date to be editable. The date on the receiving end should match the date on the sending end if edited.