Maybe he was trying to stay warm? Or dodge arrows? Or confuse the enemy?
That's another tac AI suggestion from Doms I though - it might be good to let the AI avoid walking into existing damage zones, such as posion gas clouds etc.
For example, the AI will create formations of Hydras with human troops, who tend to die from the Hydras' poison gas clouds, even by rushing into them when they wouldn't have to.
I suppose that might be partly considered part of the abstract nature of the tactical combat resolution. At least, though, it would be a suggestion for how the AI might be improved - the AI players could have their formations avoid placing area affect units near other friendlies whom they can hurt.
Although, for all I know this has been improved in Doms II - so far I've been lucky enough not to run into such things in Doms II.
PvK