I consider KJ a solid #2 RB so unless you have another solid #2 or FWP I wouldn't even consider taking him out of the lineup. Despite the low numbers he still got the ball 25 times. Also encouraging is that despite a lackluster offensive performance he did catch 2 passes.
With that said 87 yards against one of the worst rushing Ds from last year and now playing against one of the best rushing Ds from 2004? Yeah, room for concern (especially with Sledge out). KJ is still a legit #2 with good upside so I wouldn't sit him for just anybody (including a marginal WR in flex leagues).
Evil will always triumph because good is dumb.