Haphazard Bombardment states:
When Haphazard Bombardment enters the battlefield, choose four nonenchantment permanents you don't control and put an aim counter on each of them.
At the beginning of your end step, if two or more permanents you don't control have an aim counter on them, destroy one of those permanents at random.
While the ruling states:
If one or more of the permanents with aim counters on them have indestructible, select the permanent destroyed at random from among the permanents with aim counters that don’t have indestructible.
It seems odd to me that indestructible permanents are just not eligible for random selection. For example, assume my opponent controlled 3 Darksteel citadels and 1 Storm Crow all with aim counters. I would expect that Bombardment would select randomly from all 4, so there is a 25% chance the crow would die and if a Darksteel Citadel was selected nothing would happen. However the ruling seems like the Crow is guaranteed to be destroyed.
What is the Comprehensive Rule that supports the ruling on Haphazard Bombardment?