On Antelope Valley Line, the 15th drive of the journey (20:23 starting at LA Union going to Metrolink CMF) the path is set to... go through another train to reach the final objective...not sure if that is really happening at Metrolink. And well, when your trying to go around it, your path is blocked by a red signal, causing a SPAD. So, all in all, it's not possible to complete this. OK, the blocking train starts at 21:30:00, which means still around 40 minutes (just done it because I was writing this article...) to wait behind it.
He alludes to Journey mode in the OP so as per the topic I raised a day or two ago about blocking trains on Vorarlberg, seems DTG have inhibited the ability to spawn or delete running a timetable service in Journey.