There is no conflict actually. The statement in AN218241 is correct. BLE ECO and ECO are different. The BLE ECO is mandatory for proper BLE operation, and there is a crystal inside module CYBLE-416045-02 for ther BLE functionality. Therefore, even you disable the ECO in your project, it doesn't matter.
As device datasheet shows, the typical value of crystal frequency for BLE ECO is 16MHz or 32MHz. The frequency range of ECO is 4 - 35MHz. As the 24MHz crystal ECO is not loaded on CY8CPROTO-063-BLE, you can use IMO or AltHf(from BLE ECO) for SRSS.