I have a relatively high opinion of Corneliu Zelea Codreanu as a leader, but I’m pretty firmly against him being considered a saint.
Among other things, saints shouldn’t attempt assassinations.
If you believe that sainthood is a meaningful thing at all (other than, like, “a useful lie and opiate for the masses”)…this kind of reasoning doesn’t get you anywhere. Either he is a saint or he isn’t, either way it’s a fact, and the determination is not up to anyone other than God. If you want to check, the tests that make sense are things like “see whether miracles can be performed through his relics,” and not anything that looks remotely like ideological argument about his character.
…there are some broader discussions about the nature of religiosity that could easily use this as a jumping-off point, but it is very late.