"Super judgmental" for saying to close your laptop during a conference talk?

This is common, fucking, courtesy. I cannot even fathom how one would find that "narcissistic".

The part about "opening them" if the presentation is boring, though, is problematic. Who is to call that?

I don't care what my audience gets up to. If I'm less interesting than their browser, that's my problem, not theirs. If I'm half interesting but they need a distraction, then I'd much rather have them pay half attention while on their laptop than pay full attention and finish up my talk bored to tears.