Cousin and cornerman Paul Berridge, of Wanganui, said "the butcher" fought like a champion.
"From where I was and my knowledge, Rob landed more punches and controlled the fight."
Only Berridge could have left Emperors Palace with the world title after the farcical situation where Oosthuizen twice missed the 79.4kg limit at a fiery weigh-in on Saturday, finishing up at 80.55kg.
The South African forfeited 30 per cent of his fight purse - two thirds of which went to Berridge - and was stripped of the IBO belt, which remains vacant.
Words were exchanged between the two boxers' camps and the promoter Rodney Berman of Golden Gloves was furious - moving the fight out of the main event spot and yanking a planned November title bout for Oosthuizen off the table.