Funny, but this would not be sound and following this general strategy would
probably ensure you always lose out(*). Nara was offering us an opportunity we otherwise wouldn't have (to mutual benefit), and himself precommitting such that he could ensure he would not be exploited, while leaving us few other options. This is substantially different from a hypothetical where, say, Nara demanded we fork over our word halves and leave, lest he conspire against us to hand out an embarrassing defeat next round in addition to us probably not making the tournament.
The only reason we'd want to precommit to not agreeing in a situation like this is if Nara was intentionallly offering us a worse deal than we could otherwise get from him, that also wouldn't cost him much.
Incidentally, this is also why he's a trustworthy ally and Shin is not.
(*) Our situation is not in the realm of OSGT so this exact reasoning isn't applicable here, and the model is otherwise far too simplistic to use as a basis for any decisions in a more realistic scenario, but grokking it should give intuitions for why "no compromise" strategies lose out.