Even if the answer has already been accepted, more evidences can contribute to this thought-provoking topic.
I think, as it has been mentioned, eliosismology is a good way to map the interior of the star, but I am not able to argue about it.
Another disproof, comes from neutrinos.
Interior of Sun can be investigated by neutrinos detection, which do not interact passing by the outer shells, and can directly say where they come from, and how.
Standard solar theory predict neutrinos production by p-p chain.
This has been observed, even if the neutrino flux is about $1/3$ than the expected one, because of the neutrino oscillation.
Now, this theory become solid after Bruno Pontecorvo, but I do not think we have any other evidence of observed neutrino oscillation.
Furthermore, Earth's age is helping us. We know Earth is ${\sim}4$ billion years old, that is roughly the age of the Solar System and the Sun itself.
From Niels Brendt website, we know that after such a long time, the white dwarf luminosity has become much fainter then Solar (where Solar is referred not only to the Sun, but to general G2 main sequence stars). Neutron stars cool even faster. And this is obviously not observed: if Manuel's conjecture was real, Sun should be much fainter now. To this, add that they say that their supposed SN happened something like 5 billion years ago...
As a final note, I would highlight that, not only this author has never been mentioned in literature, that is (as we know) synonym of poor quality, but he actually never published (at least since 10years or so) in any refereed paper, which is automatically translated, to me and I think to the community, as not science.