Wawrinka was probably angry with himself after failing to close out the match multiple times. The advice looks bad on Wawrinka because it comes after a tough loss.
As a multiple-time grand slam champion, Wawrinka should have offered Rune advice in the locker room and not at the net following the match. Interestingly, Wawrinka and Rune exchanged compliments on social media following the match. It’s not clear whether it was their PR teams who were cleaning up the mess after the match.