That's not quite accurate.
"The Toronto police officer on trial in the shooting death of Sammy Yatim testified on Friday that his own safety was paramount in his mind that evening.“Police officers don’t get paid to get stabbed or get shot. They are paid to go home in one piece,” Constable James Forcillo said during the first day of his cross-examination. “One way or the other, I was going to go home that evening.”"
The implication of that is that Forcillo did in fact feel at risk of being stabbed by Yatim and that he fired the shots in order to stop what he saw as high potential for imminent attack. At the time of the first shot Yatim was less than 5 metres from Forcillo. Given that Yatim was also on "high ground" in the street car, he could have reached Forcillo within 2 or 3 seconds had he started with a leap to street level from the street car floor.
On that basis, the initial 3 shots at Yatim may be seen as justifiable if Yatim was, as shown by in in-streetcar surveillance cameras, moving towards the front door, was at the front door, and in position to make a quick exit from the streetcar. The remaining 6 shots are really what is in question in my mind.