Apparently the custom protocol developed with Linn supports the use of transport controls using IR remote control (Play/Pause/Stop) as per RAAT:
Two-way control integration. Artwork and now-playing information can be displayed on hardware devices. Front-panel controls and IR remotes can control Roon via the device. Volume controls on device front panels can be kept in sync with Roon. If you’re talking to a device that has multiple inputs, and start music in Roon, the input automatically switches to Roon’s input. Anyone who’s used Roon’s Meridian integration knows the value of this set of capabilities.
The roon implementation means it is currently not working. Please could you add this.