Following up on that bolded commitment quoted above, cross-partition transactions even with asset transfers (e.g. a crypto currency, not scriptable block chains) seems to destroy the Nash equilibrium also, because the cascade of derivative transactions infects across partitions, yet the validators did not validate all partitions (i.e. not all transactions).
I don't follow you. The network won't accept an invalid transaction, just as bitcoin doesn't accept an invalid block.
The way I understand it (and that might be defective) is that the other
partition has no way of validating the cross-partition tx.
If it could do that, ie. if there were an unified database, then there would not really be a partition.