How is he going to get a hold of the dude when the killer was about to get life in jail or death penalty?
There are tons of ways. The main thing is that regardless of the verdict, he'll still be in jail for a long time, and there are tons of ways of getting to him. Poisoning, paying an inmate to stab him (anonymously of course), getting a pro to take him out and so on. With a little creativity, you can get to him tons of times better by being a strategic smartass compared to that moronic way of doing it, all while not getting caught in the same way.
The only drawback with this way of doing it is that you will have severe difficulty of smashing his face and breaking his bones while he looks you in the eye, but again, this will get you punished if you do it in the courtroom (and even there, you will have problems really fucking him up, you might get a punch or two in or something).
All this will require sufficient planning and access to resources, which itself will require tons of work, but if you = up to it, this is a better alternative.
