Otherwise you could argue that prison is not the right answer to certain crimes because there could be death penalty for a atrocious enough crime.
That's not what reductio ad absurdum (fancy latin for basically proof by contradiction) means. You're claiming that the comparison is inapropriate. reductio ad absurdum means that the comparison is good, but the thing being compared to is rediculous, and since the rediculous thing is the same as the main thing, the main thing must also be rediculous, and therefor false.
> Taking away benefits cannot be compared with taking away a life.
Why not? I don't see anything inherently contradictory in doing so. Whether or not the comparison is compelling is a separate question.
> Otherwise you could argue that prison is not the right answer to certain crimes because there could be death penalty for a atrocious enough crime.
Yes you could. Lots of people do. I don't support the death penalty myself, but there certainly exist people who do and its a practise that is still extant in some parts of the world.
Claiming that overcompensation can be brought to the extreme of justifying death penalty to me is absurd, that's why I said that. But I understand that I may be wrong so, definitions a part, to me it's still comparing apples to oranges. And while oranges may be acceptable, apples definitely are not.
How? I can see a reasonable argument that its not a fiting metaphor, but i don't see how you can say its absurd, since there clearly exist countries that use capital punishment for homocide.
Edit: Also to be clear, reductio ad absurdum is a positive thing to say about someone's argument. It is not a fallacy.