...no, as in the latest FAQ (Combined 1.3 section 5. P. 21) it lists "Nationalist" as a "form/type" of an Honour Code, along with the other Negative quality types from the Ethics Codes and Other Jokes section in Run Faster (p. 22 - 32) where I expected to find it
On P. 19 of that same section it lists My Country Right or Wrong from The Assassin's Primer as being disallowed.
A "Nationalist" also doesn't necessarily need to be an assassin as we have seen in RL history which is why I inquired about it.