From the conversation I had with Akreious in a comment section, it dawned on me, that many may not understand key aspects of the lore of Metaverse, particularly the Eldritch Things and why they are enemies of the Titans and the Titan Princes. So let me explain it all in as simple a way as possible.
Also I'm doing this on a blog, because I fear it would turn the pages into a wall of exposition...
The Eldritch Things and the Tune of the Universe
Now you have to wander what makes them what they are and why the Titan and Titan Princes seem to hate them and vice versa. In the end, both sides are Lovecraftian to the point of view of humans (although one side doesn't cause automatic insanity...for the most part).
To answer this, let me use an example for the concept I plan to use. In the Lord of the Rings Universe, God, called Erdu I believe (the name doesn't matter right but let's call him Erdu) created the Angelic Spirits, Maiar (probably got that wrong but who cares) because he could. Before the creation of the physical world, Erdu and the Maiar sang a song, the tune, the lyrics would be the bases for the world to come, a blueprint. One Maiar, a pompous git called Melkor wanted to do his own thing and be in charge, so he broke of tune, and convinced others to do the same. This alternate tune, was explained to be the foundations of 'Evil'. Bye the way Melkor would go on to become Morgoth, first Dark Lord of Middle-Earth and Sauron would be his top Lieutenant.
Now let's say...the universe, Multiverse, the Cosmos, runs to a tune, a frequency, the tune...of the Proper Order of things. Things like Titans are the Epitome of such music, and all natural creature, even Ultras and Kaiju, even if they do stretch their limits, are running on this tune.
The Eldritch however, don't run to this tune. They run to a different tune, often times in direct competition with the Universal Tune. They are basically operating outside the bounds of the rules of evolution in various ways which results in their seemingly godlike nature.
Now Titan Princes aren't so much running to this tune either...but they are singing it. Each one 'sings' one or more aspect of the universal tune, that's their reason for existing, whether the tune exists without them is debatable and not to my point. Sometimes, like the trinity, they basically form bands and sing together, but their jo is to sing.
This is why, on a fundamental nature, Titan Princes and Eldritch Things are going to fight each other.
The Norozu virus is also an Eldritch Thing at the end of the day. It has a Perfect Body, which, in my words, "is an organism whose communication between form and information storage (genetics) is near instantaneous. Allowing for potentially any physical action allowed in the limits of their dimensionality"
This is a state most commonly associated with the Eldritch and basically means they can shapeshift, or even just control their own evolution as they see fit. Norozu is unique in that it is this 'and' a disease...which induces a force hivemind so it's basically an Eldritch Thing.
Now the question was asked why it couldn't be allowed to reach the level of the Titan Princes, besides the logic that they would never allow that. It's basically a song (although one that corrupts other music) going up against some singers, to give a metaphor.
Outside of Metaverse....I really don't care what you two do with it...just keep out of my stuff! Inside the Metaverse...yeah it needs to follow some rules...
I hope you guys have a better understanding of what's going on and tell me if I should put this 'Universal Tune' as an actual page, or just leave it as an example to explain things.
Differences between Kaiju Seijin and Eldritch Things
Now some may wonder why Kaiju do not qualify, and there are some that do like Zombiejiger's Strange, and Father of Darkness. But most things that we call Kaiju have a certain limitation...they are not sentient.
No matter how bizarre and strange their anatomy may seem, they are still just an animal bending the rules of Evolution as opposed to a being actively breaking and/or working against it. Seijin also are within the laws of evolition, even if they, like Kaiju, seem to bend what is physically possible. These things can be explained in some universes like Orion's, via things like Gamasynthesis and Biotics, and at the end of the day, they are the rules of the universe.
Eldritch are things like Mother of Shadows, whose powers come from outside, the proper order and who are working against that order. Seijin, invaders may be breaking some moral and/or legal laws when they invade a planet, but their reasoning are mortal desires and wants or simply bad politics. It is evil, but it is not the Cosmic Evil of Eldritch Things.