I think the move Rowson's referring to is move 9. Since in the essay he says
"Yermolinsky offered a pawn as bait, and I very nearly didn’t take it because doing so would allow him to play a series of forcing moves"
So the only pawn that was offered and that Rowson took was on move 10 in reply.
The only reason I checked was to see how far a grandmaster was looking ahead, in this case 14 moves, which i find impressive.
"...I discovered a surprising detail right at the end of the line, in which my knight could retreat back to its original square, "
Like you, I wouldn't be impressed if he only saw from move 18 to move 24.
The parent comment is correct -- "offering a pawn" means allowing the other player to capture a pawn without yourself having an immediate way to regain it, usually banking on some kind of other piece activity as compensation for the material.
On move 9 it is a simple exchange of pawns and since the material remains equal after the resulting sequence of exchanges we would not refer to that as offering a pawn.
So the only pawn that was offered and that Rowson took was on move 10 in reply.
The only reason I checked was to see how far a grandmaster was looking ahead, in this case 14 moves, which i find impressive. "...I discovered a surprising detail right at the end of the line, in which my knight could retreat back to its original square, "
Like you, I wouldn't be impressed if he only saw from move 18 to move 24.