It’s not a very elegant solution but you can require the client to place orders according to a random number generated by the server. If you can put 10 bits of entropy in there then it will be exploited 0.1% of the time.
An additional layer of defense will be the spread. If Eve sets a 2.0% offset for NuPond then NuPool won’t accept it. When the price drifts down to 1.1% before Eve resubmits liquidity there’s a small chance that NuPool will accept the order, but that probably happens, say 1/3 of the time. Overall the chance for a user to game the system is may be below 0.01%. The probability isn’t negligible, but the money-loss is.
Another way, of course, is to set up a PPC/NBT pool to prepare for the upcoming transition to PPC reserves.