It doesn't give you a choice if it is S0. If the device supports S0, and an S0 pairing method is initiated, the hub joins it S0 - no prompt to override/select non-secure.
If your device only has one pairing method, and it happens to be S0, then the hub will always pair it S0. That said, some devices (including some Aeotec for instance) have different pairing methods for non-secure and secure. Sometimes is is press device button ONCE for non-secure pairing, or press device button TWICE for secure - etc. But it is device and manufacturer dependent.
If the device is S2 you will get a popup window when you pair it with options of which security level you want - and you can uncheck them all forcing it to join non-secure. Assuming the device supports that (there are some devices that only work joined securely).