/u/GoBoltz originally pointed this out, but I thought it did a great job of highlighting what I missed saying, so I want to make to reply here.

By framing the criticism you received as an opportunity to work together, it strengthen the idea that it is collaborative. By acknowledging his feelings are valid (even if you don't agree that his criticism is), then teach him how to respond to criticism in a collaborative way.

To put it another way... While you may not have been concerned about your DPS, but he was. On the flip side, he may not have been concerned about standing still, but you were. The best way to get someone to listen, is to open to listening to them.