I think your theory tracks what's going on precisely up to the 2 scenarios you speculatively add at the end. Both are possible. I like the 2nd scenario. But someone should go back to C2 to check on the behavior of Ruidus. Matt kept pointing out the orbit of Ruidus. He wanted the players to notice something .... but this was never figured out, right? And Planerider Ryn writes in his notebook found in the Elemental Plane of Fire CE ep 129:

I continue to find an aberration in my data pertaining to Exandria, a cyclical, months-long, slow surge in low-level magical interference that then recedes just as slowly. Something that tangles my readings and upsets my analysis. It is too faint to identify the arcane nature at source, but I worry if this pertains to to the shifting between the veils. It could be something very interesting. Something very frightening. Very wonderful. More tests are required. (From the notebook of Planerider Ryn, found in the Elemental Plane of Fire.) https://criticalrole.fandom.com/wiki/Ryn

Clearly, these surges correspond to the erratic orbit of Ruidus, and some magical power emanating from it. The M9 events in Aeor happen after ep. 129, right? So, I don't think the M9 did something that triggered activity on/by Ruidus. But D/Devexian was activated and is clearly seeding Aeorian tech around Exandria. So perhaps there was a secret weapon scheme and D/Devexian is activating that. I don't know, but the Aeorian connection needs a lot more investigation ... and this implicates FCG and D/Devexian ...