If you read that 5 times over, maybe it's worth including more of the context of the phrase:

> Mr. Roth was the last of the great white males: the triumvirate of writers — Saul Bellow and John Updike were the others — who towered over American letters in the second half of the 20th century.

Seems that "great white males" refers to a specific trio of writers -- all white men -- who were seen as the giants of American literature in a specific era in history.

What's your specific objection?