Not a lawyer-type or Canadian but Googling turned up this answer: "If you have a felony or a minor conviction on your record, you may need to apply for a Temporary Resident Permit. The TRP can be secured at the border entry of Canada. If you have a single misdemeanor conviction, DUIs, and other minor offenses, you may be asked to apply for the TRP."
So Canada could reject his application (and the NHL would probably lobby hard for that). Not sure how it'd turn out though.
Re: World Cup of Hockey
Not a lawyer-type or Canadian but Googling turned up this answer: "If you have a felony or a minor conviction on your record, you may need to apply for a Temporary Resident Permit. The TRP can be secured at the border entry of Canada. If you have a single misdemeanor conviction, DUIs, and other minor offenses, you may be asked to apply for the TRP."
So Canada could reject his application (and the NHL would probably lobby hard for that). Not sure how it'd turn out though.