This is bordering on insane. Metal escalators with sharp edges cannot be any safer than stairs. Escalator steps are also higher, so if one is inclined to walk down the esalator to get those steps in then any fall is potentially more hazardous than the traditional stairs.

I suspect it was made up by the agent. As policy it would be bizarre and, as CWS wisely said, also unenforcible. What would they do if I just ignore them and walk down the steps anyway? Offload me and pay me IDB? Don't think so.