You seem to be mistaking what the claim is here.
The Claim: That Musk is in no way involved in any of the engineering side of his companies.
Evidence provided to support the claim: None
Evidence provided to refute the claim: Quotes, first hand, from some those who have worked for him, past and present, who say that he is in fact very much involved in the engineering side of his companies.
Claim debunked!
That is how claims and evidence work. In order to reinstate the claim, you need to provide two things:
1. Evidence that the original claim is valid
2. Rebuttal of the evidence that refutes the claim - you have to provide evidence that the quoted people are lying, wrong or mistaken. You personal incredulity is not evidence of anything, at least, not of anything related to the claim.
Good luck with that!