I follow both and was watching twitter when this all happened starting from Nenshi's 5-part thread that started with this tweet:
https://twitter.com/nenshi/status/818258774485962753
Which prompted Rempel's reply thread starting with her first personal tweet here:
https://twitter.com/MichelleRempel/s...72600698679296
Followed by a thread here:
https://twitter.com/MichelleRempel/s...77386634412032
Rempel initially said the cost increases are too high (and so something else needed to be done), Nenshi saying it's impossible to do anything else because of how cities are funded. As is his oeuvre, he was the first to get snarky and personal in his 5th tweet when he referred to "your government". This got her hackles up and fought back accusing him of being a Liberal and it went back and forth with neither of them looking great.
Things died down and then the following clip happened, which I do see as extremely patronizing in a way that can easily be seen as sexist. Predictably, this quote from Nenshi made things much, much worse (watch this if nothing else):
https://twitter.com/CBCScott/status/819196897105588224
Then the article came out derived from the clip above, she got mad and he sorry-not-sorry defended his comment here, basically saying he's an ass to everyone and things got to where we are today:
https://twitter.com/nenshi/status/819028812646137857
I quite admire Michelle Rempel. Her twitter takes are clever, pretty instant and are strong opinions and that gets her into some fights like this, but it's honest and I can live with that. She has no tolerance for (and goes over the top in response to) patronizing head-patting tones from male politicians.
(This kind of thing has come up in debates with former minister McCallum, and has special meaning in Alberta given how it was perceived in the Prentice/Notley debate)
As a man, it's not for me to say whether these tones are truly sexism or are just perceived as such by thin-skinned pseudo-feminists vying for attention (or whatever the criticism of the day is), but I personally don't talk to people this way and don't think others should either.
I like Nenshi as well because he's smart and refers to data and when he's not being an ass is pretty informative about his ideas. Unfortunately, his skin is super thin, and he gets personal all the time in his twitter exchanges, especially with right of center politicians. I doubt he's sexist or meant his clip above to be sexist, but he shouldn't talk to or about people that way. It's unprofessional and unbecoming for a mayor.
Basically, they're both hot-heads, but Nenshi is more at fault in my opinion.