You are correct. There is no requirement that you have a PPL to use this FAR. It recognizes the value of instruction in other category aircraft as contributing to your "education".
Most operations are used to people showing up either knowing ZERO, or coming in with a PPL or higher in another aircraft category. You may be talking to a receptionist, etc.that doesn't know all the permutations in certification.
Ask a DPE-Glider, they will tell you that your total time allows you to use this route.