Being 1-4 in the Finals hurts your legacy, but it's more than that. The logo's record in the Finals ain't that pretty either, but his legacy is still intact. And, there are a lot of great players who may or may have not reached the Finals but didn't get to win a 'chip. We do have to take into account that getting to the Finals is and always is a tough task. It ain't guaranteed. Hell, winning one is a totally different story.
My assessment of Bron's 1-3 record (1-4 if they take an L this year) is not that he just won 1 or lost more, it's the way he played in those losses. Like 2011 for example, his play there totally hurt his standing with the fans. If they do lose again this year, his legacy is definitely taking another hit as his play is way below what he is capable of doing.
As for the '07 loss, I'll give him a pass for it. He was totally not ready for that moment at that point of his career.