Question about the Klaxxi/Mantid Empire and the Sha/Old Gods

I’m replaying through the MoP storyline on my 2nd remix character, and it was at the beginning part of the Klaxxi plot where you’re flying around with the Wind Reaver and he’s explaining the purpose of the Klaxxi that I felt as though something didn’t add up.

To summarize, the Klaxxi exist to protect the Mantid Empire from the Empress should she ever go rogue and threaten their way of life or purpose. We as the player help them to awaken the Paragons because the Mantid Empire are swarming too early as a result of being corrupted by the Sha of Fear. We also eventually learn that the Sha are a sort of vestige of the Old God known as Y’shaarj. The Horde/Alliance manage to defeat the Empress and we part ways with the Klaxxi/Paragons. Later on, when Garrosh finds the heart of Y’shaarj, dunks it in the waters of the Vale and kicks off Siege of Orgrimmar, the Paragons join up with him because they’re answering the call of the heart of Y’shaarj. After a long onslaught of boss fights leading up to the penultimate encounter, we find the Paragons deep within the lower reaches of Ragefire Chasm and defeat them.

My question is - if the Mantid/Klaxxi/Paragons were so keen on helping Garrosh who had been corrupted by the heart of Y’shaarj, why were they so vehemently against the Empress who had been corrupted by the Sha of Fear, which is directly linked to Y’shaarj?

In theory, if the Klaxxi helped the Empress/Sha of Fear, wouldn’t that technically also have aided in their ultimate goal of serving the Old Gods?

The Sha were born from the remnants of Y’Shaarj, but they are not Y’Shaarj. The Sha do not work towards the same ends as the Old Gods.

Garrosh consumes the heart of Y’Shaarj and becomes more like the living embodiment of the Old God.

It’s not a super clear distinction, and Garrosh dies (or loses his Old God power) a bit too quick for us to really understand the long-term consequences. Would Garrosh have become more and more like an Old God over time? Etc.