My guess in all seriousness is that he normally wears a yarmulke and this was reflex. Schoen is modern Orthodox so that would make sense. But I defer to @jacobkornbluh https://twitter.com/Acyn/status/1359245645609984000

2/ Another possibility is that he uses his hand to cover his head when he drinks for the same reason people wear yarmulkes. (See here an "Ask the rabbi" that suggests such creative solutions" https://www.yeshiva.co/ask/382 

3/ "Jewish tradition requires men to cover their heads as a sign of respect and reverence for G‑d." https://www.chabad.org/library/article_cdo/aid/3913641/jewish/The-Kippah-Yarmulke.htm

4/ (I think the reason is the 2nd one I posited, now that this has happened a few times.)