FWIW, the FSLTL traffic injector is a specific (currently MSFS-only) addon made by a different developer/company (FSLTL, not Navigraph).
Navigraph provides the data used by the injector to display real-world traffic in MSFS. But Navigraph has no control whatsoever over whether FSLTL decide to port their software to X-Plane or not.
Also, for reasons outlined there:
I think an X-Plane version of their traffic injector is unlikely anytime soon. But that’s just my personal opinion.