I've seen a 30 moral unit fail moral checks solo repeatly, it was a lighly equipped angel casting phionix pyre, attack, goign up against undead horads. the angel averaged two deaths in combat before retreating.
Units with 30 morale seem unaffected by penalties such as starving and bonuses such as blessed. No matter what the environment the stats in battle always show 30. I don't know if that's a bug... but it seems like it.
According to the modding manual "Undead units with mentality but nothing to lose are usually given a morale of 30. They will not break but do not recieve Mindless status."
__________________
I'm in the IDF. (So any new reply by me is a very rare event.)