My response to the request for comments is:
1. The article should state what Robert Latimer said he believed – I think it would be best to actually quote him so that there can be no question about accuracy of the wording of what he says he believed. I think the article should refer to what he has said (the CBC story has lots of his comments in this regard) and not to what he believed (because no-one can know this). 
2. On the second point, I agree that it is most accurate to state that Latimer and his supporters consider his actions to be a mercy killing.