For "open source" discussion. Such peace of software can not be made open source. Gibson only own cakewalk written part of Sonar. And even then, not all that can be published.
"SONAR" as a binary file is a "bus output" mixed from tons of different libraries.
For an obvious example, look in your Sonar folder... you will see iZotope_Radius library. Not only this library itself is not a property of CW, but any code which use it (so expose the API) can not be published.