No, Nick, you are ignoring the important details. DTS support in Roon is not intentional, it is a so called happy accident. The same as in the original Apple AirPlay (AirPort Express), DTS works in Roon purely because the PCM pipeline is or can be set as bit perfect.
Roon does not recognize DTS at all – it just appears to Roon to be bog standard 16 bit 44.1 kHz PCM. Thus, Roon did not have to change anything in its PCM pipeline to pass through DTS. On the other hand, Roon would have to reengineer part or all of its audio pipeline first to recognize and second to pass through Dolby Atmos Music, hence Dolby Digital Plus.
AJ