I get it sounds contradictory, I apologize for it. The Steinmeier incident for me was just the tip of the iceberg of Ukrainian diplomatic failure in Germany, but 90% of that is Melnyk's fault. I didn't realize there wasn't a translation for the article that only talked about Melnyk, maybe that would have made things clear.
The point broken down is: Melnyk behaves like a fascist
He is representing Ukraine, so if you want to understand the situation like that you can claim this to be a war between two fascist states, we would have to fight both or neither based on that sentiment.
Zelensky made a dumb move by not wanting Steinmeier to visit, but I don't think he is anyway near as toxic as Melnyk to the Ukrainian cause, on the contrary. Without the scorched earth Melnyk created it could maybe even have been a powerful statement. The way it was, it just became part of Ukrainian diplomatic failure - which isn't Zelensky's fault, it was ill-advised but understandable I guess.