I think he already answered it quite clearly. He does not oppose equal pay for equal work for women or anyone else. The problem with the question in the debate was how it was framed. There is little evidence that this is even a problem. There are certainly individual cases that cane be cited. Yet on the whole there is not an issue here. The pay difference between men and women is most often to to due women taking on more responsibility in the home by staying home with kids for periods of time on maternity. Or in some cases job share programs. If you spend 3 years on maternity, clearly you won't be there when the promotional opportunity is presented. While women staying home more than men is a noble and an important thing to do, it is not a sign of discrimination.
For example my old firm offered a job share programs to working mothers. Two women would alternate working in customer service with one working 3 days and the other 2 days. The following week they'd switch. On a spreadsheet they are individually paid less than a man working the same job full time. In reality there combined income is comparable to the man by the hour. This is not discrimination, but rather the company making an accomidation for two women to fill the need for a full time role. It is quite easy to manipulate economic data when you have an agenda. In fact studies show quite the opposite. Working career women that never have kids are often paid more than men. The reason for this seems to be that women are more inclined to relocate than men in many cases for some reason.
Dr Thomas Sowell did extensive research into this topic. He found for example that female Dr's make less than male Dr's. Yet they also on average worked 500 less hours per year. That one full work week per month. Most of this is related to gender norm roles. If men took on more of the home responsibilities, the opposite would be true. I know my wife is home hours before me everyday, and does quite a bit more around the house than I do. If I took on her role at home my income would absolutely suffer.
The problem with the legislation proposed in congress is it is already illegal to discrimnate by gender. Any new laws are just an attempt to create more legal liability for companies in an already overly litigious society, which hurt us all. Eventually, you'll be able to file suit for lower pay even if you worked less hours.