The Montreal shooter was not unique. All of the things you mentioned here - especially hypergamy - are topics that are discussed constantly among incels on their main web forum.
I could throw a dart at Google and find you a post on the incel forum that is basically word for word this tweet.
Go browse around the incel website and you can see this for yourself. Radical Islam, anti-feminism, anarchism, anti-capitalism and general "anti-West" rhetoric are all hallmarks of the accelerationist infiltration of the incel movement.
Still nothing new under the sun.