Below average empathy is pervasive and a pretty common human characteristic, like being tall or having curly hair.
To empower those folk is how you end up with nazis, which is the point.
Your colleague does appear to have done a lot of reflection and/or reading ( feel free to ask him to contact me if he finds the stuff on my profile of interest). Most people just think Hitler=evil as the sole contibuting factor to the holocast, but I say that it's people around him, who did not have the conscience or who ignored it, that lead to his rise. There are a fair number of potential 'hitlers' around us, but it's primarily people around those dysfunctional individuals that keep them in check.
There are two types: the ignorant and the complicit. The complicit are who you have to worry about. It was seen as a means to an end and was without compassion or care of others just the personal gain of rank or power.
A colleague a few years ago went as far as to suggest that this is how you ended up with nazis.
I hope with ubiquitous communications now that we tell these people that no it’s not acceptable to behave like this! Compassion should be awarded.