[learc83]

We're not talking about your normal criminals who have some economic motive, we're talking about people who are already acting against their own self interest and to take revenge.

Either way assuming that being armed doesn't provide a 100% effective deterrent, statistics should still help us here. Even assuming a very high deterrence rate, you would still expect to see at least a handful of revenge murders of retired cops every year if this was a significant problem at all.

>provides no defense advantage should they do so

This one should be very easy to determine. How many times each year do armed retired cops thwart revenge attacks?

From what a quick Google search tells me both of these things basically never happen.