Turns out you can't glitch get Arceus in Platinum
Source: KRWL890s source
Found this video explaining the void glitch with a FAQ at the bottom of the description, specifically saying that yes, this Arceus can be shiny. However, it also says that in order to soft reset for a shiny Arceus, you have to save at a specific point halfway through the glitch ("it must be during the 1792 S step in a Jubilife City area with outdoor Jubilife City music.") or else it can cause unpredictable results.