@freh correct. Because the game is turn based, ‘multinational force’ problem can of course lead to some anomalous outcomes. But it’s a necessary evil (unless we simply ban units from boarding the ships of other nations. Which isn’t much fun).
In the case of kamikazes there are basically three possible rules:
The marine can’t amphibious assault off a friendly cruiser in a kamikaze zone if japan has any kamikazes remaining.
The amphibious assault can take place but the friendly cruiser is subject to kamikaze attack.
The amphibious assault can take place and the friendly cruiser is immune to kamikaze attack. (The actual rule).
The first rule allows japan to essentially foreclose the possibility of a multinational marine landing by retaining a single kamikaze. This is a bit gamey in its own right. And, generally speaking, we want to craft rules that encourage (not forbid) engagement.
The second rule is impracticable to code in TripleA and would require player enforcement (rolling the kamikazes out-of-game, editing the results, and keeping track of how many kamis were used). The ‘logical consistency’ benefit would, IMO, be outweighed by the hassle of implementation.
The third rule is easy to follow, is already enforced by the game engine, and is no more arbitrary than many of the other rules having to do with multinational engagement.
One more consideration that mitigates in favor of the current rule. In order for a cruiser to be in a position to unload a friendly marine on another player’s combat turn, the sz would obviously need be cleared of any enemy surface warships on the first player’s turn, at which point the kamikazes could be deployed against it. In other words, the Japanese player is not left without recourse.