I'm not even sure why this would be an issue.
Toshihide Maskawa, one of this year's Nobel recipients for Physics, will give his Nobel prize lecture in Japanese, simply because he isn't proficient in English.
I must admit that till now, I thought that it is common for Nobel prize lectures to be given in a language that the winner is comfortable in. Obviously, most tend to give such lectures in English since that is widely used. Still, I thought it would be more common than this that a non-English lecture would have been given.
But then again, in physics, English is such a "necessary" language if one wishes to publish in all the leading journals and get wide exposure. Still, great for Maskawa to stick to what he's comfortable with.