While the premise for this thread's existence is questionable, I'll take this opportunity to explain this concept, at least.
1. The Phantom Thieves manifest their Cognition of Rebellion as their costumes through their willpower, which due to representing their rebellious will, protects them from the Cognition of the Palace Rulers (i.e. their control over their pocket realities). This is stated outright by Morgana in Kamoshida's Palace.
2. Cognition is very similar to Blazblue's
Phenomena Interventio, in that it is a form of achieving various effects through a form of
Reality Warping. All of these effects are thus resisted in turn by the Phantom Thieves through their "will to rebel" protecting them from the effects of other people's Cognitions.
3. Of Cognition's many, many abilities (which will eventually have to be compiled onto a page), one of them is Mind Manipulation, as displayed by Yaldabaoth's erasing the Phantom Thieves from the minds and memories of humanity and every Shadow in the Collective Unconscious.
4. Thus, when the Phantom Thieves have displayed a resistance to the effects of a specific Palace's Cognition, then it is equivalent to them resisting mindhax on the same scale as said Palace's Cognition. And because said Cognition is what created said Palaces in the first place, the potency of a Palace Ruler's Cognition is equal to their creation feat. With Kamoshida, that's Multi-City Block resistance, with Futaba it's Large Star, with Okumura it's Multi-Galaxy, with Yaldabaoth it's Universal+. It's as simple as that.
5. Therefore, when a Universal+ scale Cognition is used in the form of mindhax, and is resisted by the Phantom Thieves, then the Phantom Thieves have effectively resisted Universal+ mindhax.