According to the node “Pustulent End”, “When a target is killed by drain life they deal damage…”. There is however, no explosion happening when an allied minion is killed.
This node is followed by “only targets minions” node, which leads me to believe it’s not just a matter of wording (target instead of enemy) but the intent is for it to explode minions as well.
Clip of the bug – https://streamable.com/r9sxob