Private 5G networks are increasingly used to support Operational Technology systems such as industrial robots and autonomous inspection platforms. These systems depend on stable, low latency wireless connectivity to maintain predictable behaviour. However, malicious or misconfigured devices can still degrade system performance by generating excessive traffic demand. While such devices cannot directly control radio resources, they can influence scheduler behaviour and consume a disproportionate share of Physical Resource Blocks (PRBs), reducing the reliability of other critical devices. This work presents an Open RAN xApp that enforces per-device radio resource prioritisation to preserve the stability of critical UE traffic in contested wireless environments.