Clearly, the request for replies from Veterans, was simply a means to gather fodder from 'heroes' that could be carefully presented to show how reasonable their 'traditional' views on anti-immigration, a woman's role in the home and workforce, and the general regression of society, in the best light possible.
I wouldn't discount it as a source, but should be noted in its extreme bias, and even if many of the views presented were 'prevailing' at the time, it doesn't make them correct.
Do you have any evidence to suggest the author cherry-picked the responses? Because there is evidence to the contrary - the responses reflect the attitudes revealed in the US army surveys.
Or is this some novel use of "bias" to mean "truthfully presents data that I dislike"?