On slavery, rights and the "common good"

A thought experiment:

Let's say half of the population of the country  is dying of a plague. There is a scientist who has a method, that only he can perform, which will save all those people. If he refuses, or stops once started, the people will die.

If that method includes killing the scientist, does the group have a right to force him to do it?
What if it involves the torture of the scientist for the rest of his long life?
What if they only have to imprison him for the rest of his life?
What if they only have to force him to work 12 hour days, 7 days /week for the rest of his life?
What about 8 hours/day?
What about 2 hours/day?
What if he only had to press a button once?
Does he have the right to refuse all together?

At what point does the imposition of the will of the masses, upon the individual, become slavery?

Whether or not he would voluntarily do these things is irrelevant. We are exploring his right to choose.

I submit that ANY such imposition is slavery. The "common good" argument is just a rationalization to allow some degree of slavery in your society.