Not quite understanding the question, but to restate:
Your apt96600 controller needs a thermistor to work, but didn't come with one installed? I'd return it. If you can't and the controller still works, then maybe do nothing and monitor, or add one.
A temp sensor will have a certain resistance (e.g. 10k) at a certain ambient temperature (e.g. 25C) that decreases as the temp goes up, so without one, the circuit will see a high resistance and assume a cold temp.
So if the protection function is to cut back power when the temp rises, it won't cut back power. Similarly, if your motor didn't have one, but the controller had an input for one, it would assume low temp and not cut back power. But, for battery temp monitoring, low temp would cut back power, since using a battery at low temps is bad for it.