Basically, if Daniel Alfredsson had joined PM between the benches, I doubt PM would have explained to Alfie which team is where and that he is there to analyze and not be a fan. So that's a bit sexist and condescending.
However, IF that had happened to Alfie, Alfie probably would have said 'Dude, wtf? I know hockey' or more likely a polite version of that. If Alfie had glossed over it and continued on in a professional manner, nobody would be coming to his rescue. The mighty Internet machine would not have sprung to action to shield Alfie and protect him from Pierre's condescension. So the fact that everyone is mad because she's a girl is, in a way, promoting the same sexist attitudes that PM is being accused of.
Kendall Coyne Schofield can stand on her own two feet and put people in their place IF SHE CHOOSES TO DO SO. She doesn't need Twitter warriors for that. She's strong enough to make her own decisions and determine how to handle herself.