Skull-related bug in Smash the Code

In the game replayed above, the opponent filled up a column by having colored blocks in all 12 spaces. Then when a row of bombs was dropped on turn 59, the bomb that should have landed on this column and pushed him over the threshold didn’t count for some reason.

Skulls just fill the enemy grid if they have enougth space to drop, else they just get destroyed.

Aka: You can’t kill a player with skulls, just fill his grid until he doesn’t have enougth space to make a valid move

Shouldn’t this be mentioned in the rules? I can’t see it there?