But "Turnabout Intruder" is specific that for TOS General Order 4 carries a death sentence. I imagine it has to do something with high treason, like turning a starship over to the Romulans or Klingons.
Wouldn't something like that have carried the death penalty all along, though? Yet back in "The Menagerie", GO 4 carried no death penalty. So it's probably something less universal that GO 4 regulates, something that only becomes an issue in special circumstances such as those Pike got tangled in.
Tracey was greedy? His defense of the last Kohm community wasn't motivated by greed, but by simple survival issues - self- and altruist. That this created a situation where Kirk was forced to arrest him then drove him deeper into a corner; using longevity as a bargaining chip was probably just another survival strategy...
Unfortunately, in this day and age looks rather it looks bizarre that there would be the death penalty for ANY crime in the 23rd century...
How so? An ever-larger percentage of humanity is supporting it nowadays... And in absolute terms, it has more supporters than at any other point in history.