Rule Clarification Needed

[Scud]

I'm playing a scenario against an opponent who failed to stack any readily available combat units on an exit hex I was headed toward, allowing me to easily escape ~66 SP's and changing a likely draw into a clear minor v on the last turn. Although I appreciated the gentlemanly play, stacking combat units on an exit hex is perfectly acceptable correct? Just not noncombat units (on the hexes or blocking the approach)? Without starting a big debate, half tracks and carriers with a defense rating would be the grey area and should be brought up before the game. Again, correct?