What was he smoking?
I'm surprised that the thought entered his head that people might not be alarmed that something which appeared to be a bomb was found in a public place. Why wouldn't they treat that with the severity it deserves? The National Post says
Jonsson said yesterday he never expected the final piece in his art project to result in such an “overreaction”, since he left a note on the suspicious package indicating it was not a bomb.
What does he think the police should do when they find a bomb? Assume it's ok because it says it isn't a bomb? The Toronto Star reports that Jonsson dialed the ROM's phone number, punched in a random extension, and then told the person that answered the phone that "There is not a bomb by the entrance of the museum". So that should be enough?
Mr. Jonsson has been suspended from school and arrested and charged with mischief and nuisance. Hopefully he'll spend some time in jail and will learn that he should think before he acts. He'll probably claim that he did think ahead, and he'll tell you how "he consulted with a lawyer from the student union before he went ahead with his project." Maybe, for good measure, they should throw that lawyer in prison too.