Should be possible. The PCAS sends information to the Garmin, but doesn't receive it back (I think). As long as you can leave the Garmin output to a setting that includes the NMEA output, you should be OK.
Will it in future be possible to connect the PCAS to any kind of Dynon (EFIS or EMS) and use the display as a kind of traffic display, showing of the situation the PCAS is detecting? Maybe you can add an additional page for this in a firmware upgrade, would be cool.