Sometimes, when civilians, soldiers, or dissidents (that is, any "private citizens") kill the enemy who attacked the colony, they may switch targets and attempt to attack the player. This will not harm the player or their vehicle in terms of damage. They will pursue them until there is an obstacle between the player and the mad citizen, such as lot's of entities or terrain.

I have observed this behavior once in my last playthrough. Colony units use the same logic as vanilla biters. What exactly happens in these situations that makes the colonist go after the player I have not been able to figure out. Since the occurrences are very rare AND I have no idea where to start looking for a fix, I will put it on the 'known issues' list. Thank you for reporting this nonetheless.