However, if someone gets physical access to your unit and there is another security issue, if the chip is active or not or even there or not makes little difference.
Correct; cutting the trace will protect you against a 'remote' attacker that will have 0 attack surface to try
anything on.
But a hardware attack directly on the PCB (connection to buses & probing side-channels) is much more likely to be successful than exploiting NFC. So an attacker with hardware access won't probably bother reconnecting the antenna.