His chin could be suspect roughly translates to: This kid is really good, nobody has really landed a punch on him.

At the end of the day he is 20 years old. Warren isn't going to risk him against any decent fighter til maye next year. I think Kahn is ready to take on Thaxton and Murray but there isn't any point rushing him just yet. Warren does need to up his level of opposition tho because its getting to a point where Kahn isn't getting chance to learn anything.