I am inclined to agree with that. County have just signed Vigurs and Lindsay for centre mid and already have Draper, Chow plus others. I doubt they will want another centre mid on the books.
I think Naismith would be a very solid and versatile addition who is still young. But at best he would be an incremental improvement on what we already have. If it's going to involve a big fee, then I think it would be better invested in the huge gaps elsewhere in the squad.
McInnes is still keen though so perhaps there is funds there to make deals like this.