Chad, you may not disagree with this law, but I highly doubt you agree with everything in the Constitution, if you have actually read it. I hope, for example, that you don't believe that black people should be counted as 3/5 of a person. But even if you do believe that then certainly, by default, you must not agree with the 13th and 14th amendments or at least part of them. The problem you run into when you get all holier-than-thou about the Constitution is that your position is untenable. The existence of Amendments that render other parts of the Constitution obsolete/invalid/moot forces you to disagree with and admit faults in one part of the document or another.
Additionally, I think you have a romantic, but inaccurate idea of what the Constitutional Convention was like. I wouldn't have been tossed out of the room for disagreeing on that point. There was a lot of heated contention and bickering about all kinds of different points. More than one constitution was drafted. The version that you are familiar with just barely passed. It wasn't 55 like-minded individuals getting together and altruistically working together for the good of mankind. It was 55 guys in different circumstances and all of them were trying to get the best deal for themselves or their particular state. After a lot of comprimising the final product of the convention turned out to be very good on the whole, but far from perfect.