Now that's an appeal to authority. Regardless of whether this person is a doctor or a billionaire or a physicist, the key points (like the issues with thermal expansion) are legitimate criticisms. "Dr Drang" presented arguments that are within the reach of high school physics.

Now, Musk may have an answer to the issues, but he certainly didn't present them. The fact that there is no obvious resolution suggests that either Musk didn't think of them or he intentionally omitted the answer (both are damning)