The restaurant is Le Roy Jucep, who is one of a handful of restaurants who claim to be the originator of poutine, who I'm sure has some sense of the origin, i.e., this was done, purely in jest, as a show of solidarity.
From the article:
The diner also shared a video on its Facebook page of a Ukrainian woman who appeared on Radio-Canada and thanked the restaurant for the gesture.
“If we were able to make someone smile over there, it’s already a win!” the restaurant wrote on Facebook.
“We are with you with all our hearts.”