You are right, but there's a way around the argument that allows them to still make a bad decision. It's called management by committee. They don't need to provide a good fit-gap analysis, sound points for the plan or quantify why it's better. You will simply hear that a group of smart people have concluded that it's a "good plan" and that they consulted with Oracle and their own experts who are also absolved of any responsibility since lack-of accountability is built-in to their contract.

It will cost a lot in time and dollars to actually get what you want and you will not want to litigate Oracle.