Say the final board in a game of texas holdem is

8 9 3 J Q

And you look down at your cards and are delighted to see

A T

For a 1 card straight flush.

Is it the nuts?

I have heard many commentators say that T K is the nuts on this board, and therefore A T Is not the nuts.

I think K T is the nuts, but i argue that A T is also the nuts since you know it isnt possible for another player to hold K T if you already have the T.