Len, I'm for certain that I remember correctly that the exit polling at the time showed that health care was the largest single issue in wether someone did or did not vote for Scott Brown.
While I think you are correct that this issue propelled him over the top, I think the bigger overall factor was a dissatisfaction with Washington and the lack of bipartisanship in general:
Nearly two-thirds of Brown's supporters say their vote was intended at least in part to express opposition to the Democratic agenda in Washington, but few say the senator-elect should simply work to stop it. Three-quarters of those who voted for Brown say they would like him to work with Democrats to get Republican ideas into legislation in general; nearly half say so specifically about health-care legislation.
. . .
Health care topped jobs and the economy as the most important issue driving Massachusetts voters, but among voters for Brown, it was closely followed by the economy and jobs, and "the way Washington is working."
Source
Reading this article, it appears they were most upset by the way the democrats railroaded the healthcare law through (instead of engaging in bipartisan negotiations), rather than a dislike of the health care law itself. The polling doesn't really support your thesis that they were voting for him to stop the health care law from passing.
While I agree that they railroaded this law through, it was clear at the time, as it is today, that the republicans were dead set against any bipartisan negotiations to pass a reasonable plan. They have made clear that they will not negotiate anything in good faith with this President. Given the way they did the same thing with Clinton when he tried to get a health care plan passed, I can't say I blame the democrats for acting as they did this time around. If you aren't willing to negotiate as the minority, then you get railroaded, plain and simple.
I have a feeling that the people in Massachusetts will show their displeasure with republican obstinance when Brown defends his seat against Elizabeth Warren.