Unless the inventory could only be reserved using Trust points, then what they told you is not true. There are certain ressies that you will run into on occasion, that can only be gotten with Trust points and if you are trying to reserve one of those, then only Trust points (rented or owned) will work…. and if you had rented Legacy points, those would not work. That said, for the vast majority of ressies, either Trust or Legacy points work, and in those cases, you can chose which ones you want to use, there is no set pecking order you are forced into and you do not have to use owned points before rented points. Hope that helps.