You only need to be competent enough to realize how markets can be manipulated to initiate a conspiracy, however successfully executing one requires a whole new master level of skill set. Off course the people with such skill set exist (as evidenced by the numerous market manipulation schemes successfully executed in today’s business world) and if Musk was smart he would hire such an expert to scheme it for him.
What we might be witnessing here is a business person that is smart enough to realize that market can be manipulated, and see a position to where they can execute such a manipulation, but not competent enough to execute a non-trivial plan without flaws. And worse not smart enough to hire a person with the correct skill set to do it for him.
The fact that his supposed plan here has some flaws is not _further_ evidence that it was planned from the beginning, that's absurd.
It seems much more likely that buying Twitter was just an impulsive decision for him that he is now regretting and looking for a way out of.
I agree with you that many supposed conspiracies require too much competence in order to pull off, and can usually be dismissed as impossible to achieve in practice. But it doesn't follow that, as a consequence, any action that would be incompetent as part of a conspiracy should be considered evidence that a conspiracy exists.