It never mattered to open-minded people ( is that liberal in the US ? confused lol ) or Canadians but the fact of the matter is that he was coming more and more under fire from the extreme right-wing. Mostly the religious ones trying to undermine everything he's accomplished as a reporter because he is gay.
Him being gay wasn't a secret to anyone althought he never said it publicly before but saying he is was just his way of saying "STFU and listen to my reports because they are honest & i have nothing to hide to bigoted people"
As a Canadian , actually french-canadian from Quebec and believe me we are worst , i'm happy for all the controversy around it .... it puts the US around the same place Canada was 40 years ago.