Pretender Cowardice?

[Cainehill]

It's well known that certain pretenders run like hell as soon as their auto-comrades have routed or died - the Moloch, for instance, flees as soon as his imps have died.

But in a test I just made, the Lord of the Desert Sun kept going even after his lions bit the dust, with no other friendly units (I'd sent him solo, to check something).

Any idea why, apparently, some pretenders flee like mice, while others do not? No berserking involved (though the LotD had Nature 9, that doesn't affect him), no magic items, no immortality. Spells cast were regeneration, field shield, and then funeral dirges, after the 40 barbarians quickly ate the 4 lions and then the Lord.