Maybe Jihoon claiming he is unbiased when it comes to Minghao (while clearly pining after him) was Chan's last straw. And, like Mingyu said, this might do more good than bad.
Joshua wants to just shrug those who doesn't want him in the group as well as his existance to in between others ship. he try to distance himself especially to Jeonghan but what happen if this move of his will affects everybody which causes the group to comfort and guard Joshua even further.