I don't have any unique authority to say it is or isn't Robert Johnson, obviously. But I have worked as a photo archivist and have had to do a considerable bit of subject identification in photographs. So I have a speck of professional background to work from. I once identified who I thought was a musical icon in an archived film but worked to authenticate that identification for months before bringing it to the public.
With that background, I personally, would be extremely hesitant to identify the individual holding the guitar as Robert Johnson. There's no provenance at all to work from and there was bias present in attribution from the beginning. The reversed image is a problem and the physical attributes of the alleged Johnson are more different than not - his earlobe for instance, the lack of a hood on the lazy eye, etc. Furthermore, I would be even more hesitant to say the other figure is Shines. The brow is very different, the eyes as well, the cheekbones, the hairline especially. I think the "Shines" in this photograph appears less Shines than the supposed Johnson even.
And a good bit of the strength of this photo being Johnson is attributed to Shines having said he posed in a photo with Johnson for a newspaper article/ad. I bet researchers are scouring extant southern newspapers from the time for that photo. The fact that two of Johnson's close associates failed to identify the man as RJ is relevant. One poster here in the thread dismisses that circumstance entirely due to their age, but I do not. I think it more likely that they would recall a person from their distant past. I've used aged associates to help identify subjects in photos but that's an anecdotal example that doesn't carry much clout and probably doesn't have any real bearing on this case. But it is a common practice in photo identification that works more often than not. Shines' daughter has said it's her father and other 'authorities" have joined the ranks to say it's Johnson and Shines. Who is correct? We don't know.
I personally would love for this to be Johnson. (Not as much as the folks who would gain financially and in notoriety certainly, and make no mistake that financial gain plays a part in this argument.) When discoveries like this come to light it's tremendously exciting. But there are issues with this photo that give me considerable pause and despite many historians, music authorities, and writers attesting that it IS NOT JOHNSON the photo is currently used to identify Johnson over verified images around the internet, including Rolling Stone magazine's list of 100 Greatest Guitarists. That I think is a big problem from a historical standpoint. It's just as likely not Johnson as it possibly could maybe be Johnson or somebody else. If the subject weren't holding a guitar would it as likely be Johnson? I don't feel that it would.
We do however have two certified photos of Johnson, and we have his music. He's a fascinating figure to be sure and because of that all types of allegations about him will continue to swirl and emerge. The fact that two associates of Johnson said that it is not him (nor Shines either) is compelling. And while it is an "alleged" photo of Johnson it certainly needs to remain as such and not take the place of confirmed properly attributed images. It's symptomatic of the very sloppy and sensationalized nature of poor journalism and social media which lacks any expertise or rigor and which has worked its way into scholarly historical research. Things do not become true simply because we wish them true, and because it would be cool.
Or else Gram Parson would have co-written Wild Horses and also be playing the piano part on it.
Anyway this is way too long and who cares. Listen to his recordings and enjoy them. They're sped up by the way and not actually representative of his playing.
You read that in a book, didn't you?!