He didn't "need" to do anything while he was still playing in the US though. Since he was traded to the Blue Jays yesterday, I hope he'll be able to play home games here and everything does get resolved. Obviously the Blue Jays front office knows more than we do and wouldn't have acquired him if they knew crossing the border would be an issue. So IMO this topic about whether or not he'll be allowed to play here is dead.
I don't get why some posters on here vilify certain players when they find out about a certain medical decision they made though. Same thing with Goldschmidt and Arenado a couple of weeks ago when they couldn't play here. Before, people on this board were glorifying Paul Goldschmidt and the MVP type season he was having. After when it was known that he wasn't allowed to travel to Canada, some posters called him an idiot or made him sound like a crazy anti-vaxxer.
In respect to Merrifield, I'm sure everything will be sorted out and he'll be playing games in Toronto. Or else Atkins wouldn't have traded for him.