Yes, 'Pete Christie' really knows his stuff. Pay attention when he gives advice.
In this case, I don't think it really ruins the picture, mainly because the exposure is good. The white background is white a featureless...and the black shirt is so dark that it's practically featureless...so the only area that really has any useful detail, is the face/head...so the viewer will tend to look there....so it works.
But in general, you always want to draw the viewer's attention to the subject's face...and you do that by letting the close blend with the background, and thus contrasting the face.
So while it can work in some situations, it's just something to keep in mind and to practice whenever you can.
Check out this link...
Perception Exercise
and the rest of that site is pretty good as well.