Makes the US look soft if we are willing to talk it over. Also hamstrings any military action. Do you think we'll be able to take the moral high ground if we attack while Jackson is in the middle of 'negotiations'?

This is probably the reason why they invited him in the first place. The Taliban's mind set: Stall, stall, stall, until winter sets in. Then by the spring the US won't have political will to send the troops in - game over.