As a typical definition, here is the BC law on trespass:
4 (1) Subject to section 4.1, a person commits an offence if the person does any of the following:
(a) enters premises that are enclosed land;
(b) enters premises after the person has had notice from an occupier of the premises or an authorized person that the entry is prohibited;
(c) engages in activity on or in premises after the person has had notice from an occupier of the premises or an authorized person that the activity is prohibited.
Since everyone who goes to a hockey game is notified that throwing objects on the ice is prohibited, that fits the definition of 'trespass'.
I was curious, so I looked it up.
So everyone who tosses a hat after a hatrick should have to pay a $200 fine just to keep consistency in the application of the law. I'm just saying that there have been many caps & octopi & salmon & rats & beers etc etc etc tossed onto the ice and I have never heard of any fines being levied prior to this. I have to wonder if this would have gone anywhere had the player been white or not complained about racial motivation.