The website announcement is accurate. Other than the three days we were closed in mid May the D&S has so far been entirely open and operating a full, normal schedule of a Silverton diesel departure, a Silverton steam departure - which is scheduled to be a 15 car steam doubleheader everyday from now until mid August, and a steam Cascade departure. So three oil steam and one Alco daily. So far ridership has been even better than 2021 so book early.
I would not expect any point at which diesels would used in place of steam.