I think you may have misunderstood. On my home security system, communication interruptions to a sensor are treated as a "bad" condition and alerts are sent with a comm warning. The system fails open.

With the xFinity system, it fails closed, meaning that when a sensor loses connection, the system assumes everything is OK until it hears from the sensor again. An alarm/alert only occurs if a sensor affirmatively indicates a "bad" condition.

Jamming disables the alarm sensors for (up to) hours, allowing thieves to break in undetected.

I'd argue that this should be called a 'false negative' rather than a 'false positive', but in any event it's certainly a security risk.