Normally would delete this because it's entirely off topic, but I'll bite for the sake of transparency.See, I'm going to be completely honest, i don't see why Pheromosa was picked before Magearna. I finished reqs and got to like 1755 while doing it, and i honestly don't feel Phero is anywhere near as broken as gear. It's buffs its got in this gen completely push it over the edge and way beyond unbalanced to me. This thing requires a Heatran minimum, and while heatran is a good pokemon and all, it can still lose if its not like magma taunt, and even then you can lose with a little bad luck. Also, screens with magearna is absolutely silly. It's absolutely easy to send it in late game or even mid game and simply win on the spot. Phero is silly but atleast it has managable ways of revenge killing it once it gets going with priority. Magearna doesn't have that atall, and i think the dumbest part about it is how the buffs it got completely removed most ways of handling it. Stored power removed Toxapex, amoongus, and sortof moltres as soft checks. Draining kiss makes breaking it almost impossible without a Heatran.
Even beyond this one set, the specs set is incredibly strong and while not as good as the set above, it's still hard to switch into and if you predict wrong it actually just claims a Pokemon each time. While less common i will say that shift gear physical magearna is also atleast worth mentioning as a set, as it turns heatran into a free kill and perhaps the game on the spot if screens are up.
I'm not personally sure whether i feel pheromosa is broken or not, I haven't played for too long in this meta, but i can honestly say for certain that magearna was worse.
Magearna was not picked to be the suspect and it was not even really considered for a number of reasons. First off, it received notably less support than Pheromosa from the playerbase survey. Both Pokemon received more than average amounts, but it was clear more people found Pheromosa problematic. It is also worth noting that this survey was before Quiver Dance Pheromosa even surfaced in the metagame, which in the opinion of many pushed it over even further. Second off, Pheromosa has been on the council's radar for far longer, the subject of many more (entirely justified) discussions in this forum, and previously was just 1-2 votes away from being grouped in the first slate of quickbans. Meanwhile Magearna did not even qualify for that slate and has been only discussed sporadically, with your post being one of the first to call for it to be suspeced before Pheromosa or Spectrier. Finally, the council was unanimously in favor of suspecting Pheromosa, with some people even contemplating if it was quickban worthy, whereas the support level was not the same for Magearna at all.
I am not even going to get into responding to your logic because this is clearly not the place. I personally believe it is plausible we see an SS OU with Magearna suspected in the future despite this, too, but this is simply not the thread for discussion of it. There is a metagame discussion thread, a hyperlink to PMing the council in the OP of this thread, and my personal PMs are always open if you do not want to message the collective. There are numerous outlets to voice complaints about the system and I have went well out of my way to be transparent, so seeing posts like this with potential to derail the suspect thread is disappointing.
I am only leaving this up to make an example and say that any future posts that derail the thread will be deleted and potentially infracted. And as I said before, there are numerous places that are easily accessible to voice these opinions and I am always willing to hear people out, so do not hesitate to use them.