MAD underpinned the Cold War nuclear calculus. With nuclear weapons that would be certainly be fired in retaliation to any pre-emptive launch, it entirely disincentivized any such pre-emptive strike. Within the defining framework of such knowledge (which assumed decision-making power structures were rational as to each side’s own interest), something like normal diplomatic relations and, for example, weapon reduction treaties, were possible.
Yes, game theory often concerns itself with matters that are far from a game.
The relevance of this point for MGA arrangements is that if they are one-sided you cannot establish normal relations that should ensure the spoils are fairly shared. If a carrier is able to exit at short notice “for convenience”, it holds unreasonable power over the MGA. But equally the MGA needs to accept submitting to sanctions should it fail to meet reasonable targets. Only within a framework bounded by each party’s power over the other will there be a fair ability to operate and negotiate long term mutually favourable outcomes.