I said:
"I would be happy to kill any scientist or doctor that actually thinks they have a right to harm or murder humans [and of course, acts on this belief] in the name of science or "progress"."

Not:
"I would be happy to kill any scientist or doctor..."

The point was *if* they are harming or murdering humans in the name of science or "progress".

Killing Nazis doctors which were experimenting on retarded people, gays, criminals, and/or Jews, was a good thing and I would be happy for all of them to be hanged, shot, or whatever. Their deaths should a day to celebrate.

This of course assumes was a degree of certainty that these doctors had done these crimes. And realistically in most situations the only way one can hope get this kind of certainty is by having a trial.
But suppose they had a trial, and because of technical problems, they were released.
I would not be happy.
Happy if killed or sentenced to very long prison terms [prefer death, but would accept long prison terms].
And unhappy if not severely punished.

But this doesn't mean I would take the "law into my own hands" if I'm unhappy. Now, if these doctors who got released did something which involved me on a more personal level- the victims included killing or maiming my mother or brother, or whoever, that might be different matter- that is hard to know.
Or if someone in similar situation murdered such a doctor, I would have a tendency to want a reduced sentence.

So to repeat: I would be happy to kill any scientist or doctor that actually thinks they have a right to harm or murder humans [and of course, acts on this belief] in the name of science or "progress".

It would be a honor to kill them. Getting the Nobel peace prize would pale in comparison.