One of his concerns was that prior to the law, people with pre-existing conditions were unable to get insurance.
I don't do very well in short, on-the-spot conversations (how can I briefly explain that our current system of pre-payment for medical care by third party payers is not actually insurance?) but I do think about them later so if the issue ever rises again, I will be better prepared to respond. Here's a bit of retrospective my thinking.
If someone supports ObamaCare because of a sense of concern about the disadvantaged, a key point for me to make is that being compassionate is also a value for me-- BUT, I do not view coercion as compassionate. One of my primary goals is that we as a nation or a community find solutions to life's challenges that preserve a standard of voluntary interaction and that never condone any initiation of force.
In regards to pre-existing conditions and insurance, I wish I had said: you can not and will not help people who are sick by destroying the insurance industry, which is what the legal requirement to cover pre-existing conditions will do.
Coercion is not compassionate
The good is destroyed when you abandon voluntary interactions in favor of force.