While it doesn’t change the status quo, it sets a major precedent that passenger rail is not important, and it’d require repealing, which may be difficult depending on who is in Congress (or the President can just executive order it out) if a future president puts measures in to enforce the existing bill where Amtrak has priority.
Another issue is that a number of major destinations and routes Amtrak runs on are often near ports, especially on the West and East coasts and there are many rail yards so basically Amtrak is in a lose-lose situation.