Yes, explanations should be provided, or else the word "snub" has no meeting in this context.
Also, as it happens, I also don't agree with your assessment of his performance. I thought he was very broad and lacked the subtlety the role should afford. He wasn't as good as the material. So, I don't think he was snubbed, let alone think his "snubbing" need no explanation.
Words don't deserve that kind of malarkey. They're innocent, neutral, precise, standing for this, describing that, meaning the other, so if you look after them you can build bridges across incomprehension and chaos. But when they get their corners knocked off, they're no good anymore…I don't think writers are sacred, but words are. They deserve respect. If you get the right ones in the right order, you can nudge the world a little.