per p.26 of SBH:
The only way a routing model can be surrounded, and
thus automatically killed, is when no matter where it
moves, it will have at least one active (i.e., not Fallen,
not Transfixed) opponent within 1x Short distance.
i assume that that check is made relative to the end of the Short Stick, not along its length? Otherwise it becomes possible to surround an enemy using only 2 models because, as it says earlier on the page:
Fallen or dead enemies, or the enemy that the model is disengaging from if he was engaged in melee, do not count.
i have to assume (for sanity's sake) that "the enemy" should read as "the enemy or enemies". If that is not the case, then any unit becomes surrounded (for Morale failure purposes) the instant it is in contact with more than one enemy, regardless of the orientation/placement of those enemies.
e.g. two units (X) are engaged with unit Y:
If we take the above text literally (i.e. in its singular form of "the enemy"), then unit Y always has another unit within 1x Short: no matter which one of X we count from, the other X is within 1x Short. Thus my assumption (from above) is that 1x Short limitation is counted only at the "end of the stick," which would allow Y to flee 45 degrees to the top/left.