Forced Unloading Movement

[rules_heretic]

But what if the INF unit is disrupted from being hit on the truck. They unload into an already full hex they are to be disrupted, but since they are already, nothing?

There is no additional or compounded disruption. The unit would be displaced to an adjacent hex or be eliminated after unloading.(Emphasis mine.)

Per your original rules post (which was a digest), the opponent would pick some unit, not necessarily the triggering unit to be displaced.  (I'm not looking at the rule, just the info above.)