Yes, I think that is right. Look at the quote in the context of the story. Rand had just been shielded by a circle of 13 despite that he had ahold of Saidin. The ease with which they shielded him was fresh on his mind when he had the thought.

Rand was saying that the only way 3 women could be certain to cut him from the source, 100% of the time once he has taken ahold of saidin, would be if the 3 women are of Semirhage or Mesaana's strength.

As for the interesting twist, I find the above example a good comparison with the example of 2 regular Aes Sedai + Moghedien in a wig.

The Semirhage/Mesaana example above tells us exactly the point at which Rand would get overwhelmed no matter what he did.

The Moghedien + 2 AS example above tells us exactly the point at which Rand actually becomes threatened. Everything in between those two points and the winner depends on other factors: such as skill, knowledge, dexterity, location, luck, etc.

Apparently Moghedien + 2 AS is NOT a guarantee win for Rand, but anything less and Rand wins every time.