That one is actually pretty black and white if you follow the actual definitions of the word, provided that definition comes from Oxford... If it comes from Merriam-Webster, they allow "physical activity engaged in for pleasure" to count, in which case scuba would be a sport
My take is that words don't have meanings, words have usage.
If a large amount of people use a word in one way, it is correct, dictionarys is descriptive, not prescriptive, and they are not up to date.
But my own definition of the word sport, it have to include smoke from burnt rubber or gunpowder. ;-)