Some singers close their eyes and some don't. I do a lot of the time when I sing and noone's complained to me.

Standing/sitting; eyes open/closed; beard/no beard; Guinness/no Guinness. These things don't matter to me when I'm listening to a song; I have more important things to spend my energy on!

If something's done as an affectation, it can be irritating; otherwise, does it really matter?