Ideally he should have been challenged on it, but I wouldn't judge people too harshly for not doing it as it's just an incredibly awkward and unexpected situation to find yourself in. The main thing is that he isn't given a second chance because that would be the real sign of having shat the bed.
It’s good to see this being widely condemned on here as well . A few years ago there would have been a slew of apologists giving it 'how come it's awrite to call someone a fat or baldy b*****d but no a black wan?'.