For the same reason the opinion of someone like Rupert Murdoch matters. Its not about their viewpoint directly as an individual, its the fact they control massive platforms that can and do sway public opinions.

In murdochs case he’s had an influential impact on British politics over the last 40 years and has used his media empire to act as a king maker.

Musk isn’t as savvy or as intelligent as Murdoch but that doesn’t mean is influential position should be ignored.