You really nailed it with this part: “The laser may not even need to damage the missile. Just the superheating of the air on that side of the missile is going to disrupt the symmetry of the airflow around the vehicle.”
All mirrors (even if feasible to attach) would do is INCREASE the heating of the air on that side of the missile by redirecting some of the energy back there.
The “they’ll just coat their missiles with mirrors” meme is a fallacy possited by the left to denigrate the technology in the eyes of a scientifically ignorant public. After all, the dollars “wasted” on actual national defense could be better spent buying votes...
He did a very good summation