Wouldn't be surprised if that provision was added in conf.
It's quite common, or was under the Republicans, for provisions to be added to bills in the [link|http://en.wikipedia.org/wiki/United_States_Congress_Conference_committee|Conference Committee] that resolves difference between House and Senate bills. The members of that committee are appointed by the leadership and they have a lot of leeway in adding things - things that aren't even in either version of the bills. As such, it wouldn't surprise me if it was added there - where most of the congressmen and senators wouldn't have seen it.
That's one reason why the leadership is so important even if they don't have a large enough majority to push through their agenda directly. They still have a big impact on shaping the legislation, and it's a big part of the reason why the Republicans were able to change so many things even though their majority was small.
I haven't taken the time to investigate the history of this particular bill, so I could be wrong. But in any event, I wouldn't expect that the people voting on the bills will read them more closely as a result of this. I would hope that they would encourage their staffs to watch the legislation more carefully and alert them when things like this appear.
[edit:] I've looked at the legislation some more. The language in question [link|http://thomas.loc.gov/cgi-bin/query/F?c109:6:./temp/~c109SaeWhQ:e177847:|Section 502] in the final bill is not present in the [link|http://thomas.loc.gov/cgi-bin/query/D?c109:3:./temp/~c109SaeWhQ::|House version] (where there is no Title V section at all), nor in the [link|http://thomas.loc.gov/cgi-bin/query/D?c109:5:./temp/~c109SaeWhQ::|Senate version]. It seems clear the language for all of the Title V provisions, including Section 502, were added in the Conference Committee. It's really not surprising that few knew what was in the bill when it came up for the final passage vote.
I've seen mention of the name of someone who pushed for the 502 provision, but haven't seen anything official in my scanning of Thomas at the Library of Congress site.
Note that if these links don't work for you (due to my search timing out), a search for "HR 3199" for the 109th Congress [link|http://thomas.loc.gov/home/multicongress/multicongress.html|here] will give the various versions of the bill. H.R.3199.ENR is the final version (you may need to search for it separately).
Cheers,
Scott.
