Is the Black Face ever okay?

A Child, 10 years old dressed up as his favorite player El Hadji Diouf in full attire and a black face....sure Diouf and the Leeds players found it funny, but is a blackface or head (in this case) ever okay? The fan met his favourite player outside Elland Road ahead of his team's home game against Bolton Wanderers on New Year's Day.
Smiling: The super fan poses with his hero El Hadji Diouf 
Hero: The child posed with El Hadji Diouf again in the tunnel at Elland Road
After an outlash on twitter, media, social networks, the boy's  father had to make a public apology for his son
''I want to apologise if [my son] dressing up has caused offence.He asked to dress up as Diouf so we let him for a bit of fun. We completely underestimated the response it would get. Hes only 10 and likes the banter so lay off please thanks for positive comments'.