A post on Pan Am Railfans FB page says people were seen in a meeting on board as train passed through Shirley so it doesn't sound like a dead head move. Also a video posted on that same FB page shows that this OCS is a 2 car consist with PAR 1 leading Syd Culliford and ST100.
Lastly, a poster did an imaginative, realistic looking rendering of PAR 1 in a combined CN, CP, CMQ (proxy for Fortress), NS, G&W, and GRS paint scheme as the pocket-sized OCS passed through East Kingston . Pretty funny stuff!