Exactly. The death penalty has been considered legitimate, although certainly not something to crow over, but something necessary to protect society. It was the emergence of the left, which became powerful in the Church after Vatican II, that confused the issue.
The Left has subverted many Christian churches, not just the Catholic Church, since WWII.
Even today the Left seeks to twist the voting power of those who still believe. We are told that we must empower the socialist agenda of health care, cars, internet, etc. for the poor because we need to be compassionate with the poor. EXCEPT there is no charity in paying Caesar his taxes.
When truth is open to interpretation,justice can be shaped and formed by persons who have control of the means of communication. This control is often not based on any commitment to good,truth or beauty,or any moral absolutes,but rather is based on whichever person or group has been powerful enough to wrest control of a society or nation and what they determine to be in their best interest.
Consequently, there could be a great concern among some of the good prelates that in the near future,the death penalty could be carried out arbitrarily,capriciously and even whimsically. So it could be that they see this on the horizon and believe that caution may be the better,nobler path to follow.
Looking at the world today,I think they may be right although it is not my personal preference at all. I certainly hope they make no more changes in Church teaching on the subject. They have gone as far as they can to prevent the above scenario from happening and enough is enough.