Ok the solution was to set their animation on the attack to 0sec and the backswing animation to something greater than 0, so the creep never effectively attacks the tower, but it still triggers my trigger (I didn't copy/paste, just typed it from memory):
Event:
A unit owned by player-1 is attacked
Condition:
Owner of attacking unit = player 5( yellow )
triggering unit is a structure
Actions:
Wait 1 second
Order Attacking unit to move to the middle of Destination
This makes it so that if a player does block a move point, the creep will attack then be ordered to move the Destination point. Seems to work, but i'm not terribly happy with the fix..
-Verbal