It's extremely disrespectful to call the people from minority and diminishing cultures racist or white supremacist for protecting their own culture. Birth rate / demographic / cultural shifts are real problems. Elon has never talked about "white people" or their superiority. These issues have nothing to do with skin color. Same issues are faced by many asian countries as well.
>> Elon has never talked about "white people" or their superiority
I would encourage you to try to avoid making such easily falsifiable claims, and put at least some token effort into your arguments. I was able to find the below with less than five minutes of searching.
He has also repeatedly advanced a version of replacement rhetoric (e.g. claiming Democrats import immigrants to change power via the census), which is essentially a repackaging of the Great Replacement idea, i.e. a racist conspiracy centered on replacing white populations with those from other races and ethnicities. You can, for example, read the transcript of his interview with Don Lemon.
So yes, Elon does in fact frequently talk about white people. Even when not explicitly mentioning them, he means them. For example when he says people should have more babies, he specifically means white people: https://newrepublic.com/article/181098/elon-musks-weird-obse...
>> Same issues are faced by many asian countries as well.
I find your comparison of this issue to issues faced by various Asian countries to be pretty odd, as it does not stand up to critical scrutiny. Asian countries' demographic crises are about internal low fertility and rapid aging, not about being "replaced" by outsiders. Indeed, the arithmetic makes the comparison impossible: Japan, China, South Korea all have extremely tiny foreign populations. Therefore, pointing to Japan/Korea/China's low birth rates to sanitize "replacement" talk is a bad-faith pivot.
I don't see how you conclude that Elon is so focussed on white people. From the articles you posted, it seems more about culture rather than skin color.
The only times he seems to talk about "white" people is when these people are being prejudged for their skin color.
Demographic change can be caused by just a low birth rate, which is more of an economic issue, but it can also be combined with immigration, which may result in changing culture, i.e. "replacement". This issue is currently mostly faced by people who are white Europeans, but these people also represent many different local cultures. Not to mention that Japan and South Korea have also been increasing their immigration, although it has been quite low so far.
All kinds of people have equal right to defend their own culture. It doesn't mean that they're supremacist or racist, even if they think that their culture is better than some other culture. It's only supremacist if it aims to destroy, repress or subject other people, by advocating discrimination and violence.
Thus, "make more white babies" is not supremacist or racist. As isn't calling out violence against white people in South Africa.