If a Serco and an Itani are within the same group, the "closest target" function will currently target the Serco (if you're Itani) or Itani (if you're Serco) regardless of the fact that you've set aside your differences to pursue a common goal: namely killing hive bots.

More directly: the closest-enemy function ought not to target members of your own group, regardless of their race and yours.