I don't know why you're so interested in sexism and misogyny, bro! I can't see what that has to do with anime at all.

ETA: Also, um, wow, there is a lot going on with the idea that a viewer is "not present" while watching a show.

Zac isn't the first person I've heard the voyeurism angle from concerning K-ON!, in particular. In this type of anime, the viewer's presence is completely irrelevant. If K-ON! was an anime with pantyshots all over the place and the camera focusing in on them (I.E. "Male Gaze"), that would be voyeuristic, but K-ON! isn't that kind of show. The characters aren't girls you're looking at through a keyhole. It's more like you are the room that Yui, Mio, Ritsu, Mugi, and Azusa are eating cake and drinking tea in. Nobody's trying to arouse or please the room. Things are happening, but the room is just there, existing, but irrelevant to the events.

Your options are to be a male viewer or the room. There's no way a viewer could possibly take the point of view of the girls.