When you take an historical and comparative perspective, the US really stands out as a laggard with regard to comprehensive social policies for women. This should be an important part of your discussion. We got the last laugh on that, though the fight to guarantee those rights continues. Martha Griffith and Katherine St. George were prepared to offer the amendment, but they let Smith do it because they knew he would bring more votes than they would. But smith knew that the bill was going to pass, so it was unlikely he would have added an amendment like that just for the hell of it.
Someone needs to research why and how the myth was started.
But I'll make an educated guess. Adding protected classes to the bill did not invo lved calculations of resource allocation. But implementing it did. Furthermo re, one third of the compliants the first year concerned sex discrimination. To do this they gave speeches, Issued press releases and otherwise spoke to reporters and authors, who blindly took their word for it.