Request for netiquette advice

Among my f-list there is a particularly nice and charming person, whom I do not know all that well, but whose posts I enjoy. Just recently, two people whom I detest and whom I barred and blasted from my LJ in two separate incidents for very good reason have turned up on her f-list and started posting fairly frequently. These are people I would cross the road to avoid. I am seriously wondering whether it would not be better for me to de-friend this person, not for any personal reason, but because I do not want to share any space with certain other individuals. Does anyone have any thoughts?