For one, veracity. There are lots of unsubstantiated claims similar to this one, just look at the National Enquirer if you’d like an example. This one is real, with verifiable proof, meaning we can use it as a foundation to build more knowledge on top of. Seeing as there is no moral or ethical way to remove someone’s left frontal lobe as a science experiment, it is as close to a case study as we are ever likely to get.