It definitely is. Mostly other teams' fans though.
Are they arguing rationally though or just that in the moment it seemed like it should've been a penalty because of the optics of it generating a scoring chance?
The replay clearly shows Letang's one handed grip on his stick flailing at the loose puck somehow had enough force generated to send the Flyer jumping into the air. Challenge anybody to explain that logically without concluding it a dive and I'll accept it's anything more than biased whining because of how much they don't like the Pens.
I guarantee not one person will objectively look at how blatant a dive it was until emotions have died down. If that was Crosby literally jumping into the air to draw a trip this site (especially) would have a conniption fit.