The weakness of Tsukuyomi is that any one with the Uchiha KKG and the Sharingan can break out of the Tsukuyomi. This was the weakness he was referring to. This genjutsu is special and not meant to be counted by RSM/body users. It isn't a standard Sharingan genjutsu where the Tailed Beast can break it for you by lending their chakra.
Dude stop referring to hypotheticals because the manga sets specific conditions to break Tsukuyomi. Having control over their chakra flow or even detecting the Tsukuyomi doesn't prevent them from getting caught within the genjutsu. This means that the Hyugas get raped, Hashirama and Tobirama get caught. This isn't like Orochimaru measly control which he put over Tobirama which he broke for an instant. Its the strongest genjutsu.
It's not hypothetical, the time Itachi spoke about Tsukuyomi to Sasuke was when he had the intention of manipulating him.
He wanted his little brother to believe only he had the power to fight him an no one else because his aim was to make Sasuke strong through his methods which he later admitted as wrong. By saying Sasuke needed the "same blood" he was basically re-enforcing the idea that Sasuke had to fight Itachi alone without team 7's help.
He even told Sasuke that he needed MS to fight him yet Sasuke proved his claim wrong by breaking genjutsu with 3T Sharingan instead of Mangekyo, that in itself basically puts everything Itachi said into question.
Furthermore, if Uchiha blood is all that's required to break genjutsu then Kakashi should have been able to break it since he was capable of using Uchiha KKG of the same level as Itachi.
It's evident that the Sharingan allows your to see through genjutsu but not break it. Genjutsu works by controlling the opponent's chakra flow, and disrupting the user's control over the chakra flow occurs when you
release chakra which is known as Kai release.
When Sasuke broke Tsukuyomi he
released his CS chakra, and because MS chakra is of th esame potency as CS Level 2 he managed to break it without a Mangekyo.
Therefore it suggests that when the victim has chakra as strong as CS or Senjutsu they should be able to break Tsukuyomi.
And Hyuga should also have the potential to break Itachi's genjutsu due to the fact genjutsu works by controlling the flow of chakra in the opponent's body and they have the highest level of control over chakra flow in NV. Not to mention, genjutsu is a Yin feat and Hamura had stronger Yin affinity than Hagoromo.