Although I see Tim's point, I don't agree 100%. First, regarding voicing, this is a valid one and as ggcg commented similar ones do turn up in e.g. classical guitar music. It's different from the more typical jazzy voicing with the 6 on the high string, but I wouldn't say either is inherently better or worse.
Also, the fingering: while definitely questionable or at least adventurous, it may not be only an error. This can be done without flipping the guitar, but you do need to turn the hand, grabbing the neck from above instead of the standard position. Then use the pinky for the bar, and the index and ring finger as specified. A bit crazy, yes, but I'd say it's an interesting idea.
For what it's worth, I personally can play the described voicing with barree-1 and ring&pinky for the d&f, but I can't do it in the upside-down hand position because my pinky is not strong enough for the bar. However, I can do the upside-down position higher up on the neck (where the bar doesn't require as much force as it does on the 1st fret).