Nah I do believe that it was right to open an issue, and also that the code should've been credited. But it is now. Also I mean... yes? How else would you expect for them to find the code? /kbin is a project with quite a few eyes on it now. If you upload a project that nobody looks at, of course things like that go unnoticed. Doesn't make them less wrong.
But all is well that ends well. If you do anything in the public, you gotta be prepared to deal with people who might not be the friendliest. That's fine. I think defusing the situation like was done here and immediately fixing the problem was exactly how this kind of thing should have gone. It's on all of us to defuse tense situations, whether we're bringing up an issue or responding to an issue brought up by someone that might be offended. Kinda like how you should be driving defensively to avoid any accidents before they can begin to happen. I guess? Oh god I'm making too many driving analogies today I really gotta stop.
[edit]: I'm also not trying to call out the person opening the issue. There are many ways why it might have been worded like that, including past experience. People are very complex and seeing just a snippet of them like this isn't what we should immediately base all of our judgements on.