I mean, at least in this summary (the article is pay-gated) it sounds like his point is valid. The line, "The fact that he was a soldier does not mean that he was a Nazi.", seems suspect, but I assume by "Nazi" he means the ideology or the political party directly, which could be true. Again, working purely off the summary. As Himka stated, those in Ukranian divisions may have been motivated to volunteer by fear of continued Soviet atrocities after witnessing the Holodomor and other crimes against humanity, or by vengence for these crimes.

If Yaroslav Hunka did join for these reasons, I think the matter is a lot more grey. If you watched your family and friends die to a violent, genocidal government, its not weird that you might be willing to work with another if you think they're a less immediately dangerous. Of course, if thats not the case, or he did support the Nazi party, the ideology, or if he was involved in any of the division's war crimes, then all of this is out the window and he deserves to be punished to the full extent of the law. My point is that he should be proven guilty before being counted as a supporter of the Nazi ideology, and there is still room for error currently (unless there's social media posts or other evidence I don't know of).

Edit: And just to be extra clear in case it wasn't obvious, I think supporters of the Nazi ideology, its modern incarnations, facists, and racists are all terrible. I think anyone who supports these belefs should be denounced and avoided. I just also believe that it is important to be certain of the accusation of something so awful before condeming someone for them.