My impression is that if two viruses are ONLY "96% identical" "throughout the whole sequence of the viral genome", they shouldn't be described as a "close cousin". Should it be called a "not-so-close cousin"?
Humans sequences are said to have lots of pairs that have no known function, and lots of pairs that have no relevance to a given question... hair eye skin color, arm length, gender, etc might not impact death from virus. Even if virus are coded efficiently, a 4% diff could still retain function of the 96% that counts kills. Yes, more people will have to look at it all to know. And whatever the 'truth' of Corona may be, it has become political, so like 9/11 may not be known for many years, or at all. And even without DNA, the 'it came from China" claim could alone be levered to start wars.