The PollingRate property is actually for the purposes of integrating with the Chart component, but it was written before we did a fairly major overhaul to how the documentation gets generated from the source code. That change causes the Javadoc information to get used for describing properties, and here you're seeing how that Javadoc was written internally and hasn't been updated to reflect the procedural changes.
Normally, the BluetoothClient only reads data from the connected peripheral when you call one of the Read methods on the component. To support realtime graphing of data in the Chart component, the PollingRate property was added to periodically read data from the client and report that to a connected ChartData2D component. In hindsight, as the design for the system evolved it would have probably been better to make this property be a property of the ChartData2D when a BluetoothClient is specified as the component's Source. This is what happens with other components, like the Spreadsheet or Web components.