I am not going to answer the question that you asked. "Too obvious" is off topic.
Instead I am going to answer hopefully the real question, "should I do it?"
I think your readers will fall into 1 of 3 categories.
It totally goes over their heads. To these people, it does not matter if you do it or don't.
They find out about it from a 3rd party. They are going to go, "OK, i guess I heard of Nirvana" They may be annoyed, they may move on, they may imagine the author as some 90s kid. Not much benefit.
They like Nirvana well enough to get your reference. Great, they got it, maybe they like you as an author more for it, now what? If they are there for one scene then it does not matter, everyone has fun and we move on. If they are there for the whole book then we have problems. These wolves are forever tainted by being these people. Readers will pretty much imagine their faces over the wolf snouts. If your work is meant to be funny, great. If it's not you have now sapped much seriousness out of it. Worse this will now affect you. You are now connecting these wolves to people, and it may affect your writing.
My main opinion is that this is not an Easter egg. Most likely this will one way or another become a running joke for as long as the wolves are in scenes. If you want a running joke, go for it. If you don't then be more subtle.