Thanks for the précis, the abstract didn't reveal much about the conclusions (and I no longer have library access to journal papers).
The impression I get: Everyone knows NOx can be a huge problem, there are several workarounds. My own take: If good workarounds are developed quickly it may just save ammonia as a fuel and could even be cleaner than diesel scrubbers. (All that still doesn't do anything about the NO3 toxicity though).