I know you are being facetious but technically the article is making the argument, perhaps tongue in cheek, that Halloween as practiced in Canada and the US, is cultural appropriation. 

Personally, I think there is a difference between cultural appropriation's intended meaning and the inclusion of the cultural practices of an immigrant population into the mainstream practices of a country's dominant culture. One implies the co-opting of the traditions of marginalized peoples by those with greater socio-economic power for the purposes of profit. The other is a natural melding and acquiring of the cultural traditions of other peoples through global contact. It's how cultures have always been influenced and evolved.  

The Halloween tradition was introduced to North America by Irish immigrants fleeing the potato famine. As they became integrated into North American society, their cultural practices and traditions became absorbed too. It's now as much a Canadian tradition as an Irish one.