Veitch didn't create Sidious first off, and up until that point, Veitch had created most of them...KJA wrote GAOTS and FOTSE mostly himself.
The difference is, Veitch didn't 'create' Sidious and he's talking about the TOTJ era, not DE. Veitch created the concepts of the ancients, but KJA filled in the blanks. I don't see how this means anything towards Sidious since they're discussing TOTJ and TOTJ alone. It does show KJA might consider the strongest title between Kun and Sidious, but that's it.
While it may be true that countering TK is basic, Yoda's power is far and away above most Jedi, so I dubt most could counter him if they tried.
And Sidious could go for force lightning on traya, which'd be roughly the same thing, or even use the drain on her. And we're considering that Sidious wouldn't have learned of these 'unblockable' techniques from the ancient Sith he was talking to, he'd obviously consider any other Sith Lord a threat to him.
Oh, btw, just a note: Apparently the Jedi did kill darth Bane as in the novelizations, Mace mentions the 'fall of Darth Bane a millenia ago'.