Seems to me that when choosing friends, race is unimportant, leading to the statement "I'm not racist because some of my friends are of X race".
However if the 'dumb statement' (I assume a racist generalisation like 'all people of xx race smell of lavender') is based purely on the race, then they're including their freinds in that.
Effectively, it's a double standard. Either:
a) All people of race x smell of lavender, except their friends (so it's not true: not all people or race x smell of lavender)
b) All people of race x smell of lavender, including their friends (so they are being racist)
either way, something is wrong : they're ignoring the overlap (in sets: the intersection) in their statement and their group of frinds of race x.
A racial generalisation is poor logic anyway. It's the same as:
I saw a man with a briefcase barge into an old lady
all men with briefcases barge into old ladies
Even if you see this a few times, it's blatantly not safe as a truth.