Havocs have an ability called target lock, which as you guess would target enemies. However it’s also coded to target neutral units; and it just so happens that Amon’s Champion (Chain of Ascension) is counted as neutral, and is targeted by the Havoc. I’d like to believe there is no change when the champion is targeted, but I am generally asking to code out targeting neutral characters. It serves no purpose nor in any situation would really give a benefit to the player.
I noticed this too while playing, I usually make my units destroy neutral units through the attack command in order to avoid this.