I think you can be flexible about this and would say that, in my opinion anyway, the use of 'none' has come to mean not only 'not one/no-one'. It also now covers 'not any', and thus can take a plural verb where appropriate.
"Is there any sugar?" can be answered with "No, there isn't any", but also with "No, there's none." (= not any + singular)
"We're all really tired, so none of us are going to the cinema tonight. We just can't be bothered." (= not any + plural)
"Are there any people left inside? No, there are none." (plural + not any)
In the last two we want to emphasize the plurality: 'we're all not going', rather than 'not one of us is going', 'people' rather than 'person'. This also makes your quotation reasonable, as 'the brave' refers to 'all brave people'.
I have a feeling this may be disputed. :-D Fire away!