I don't see how you can simultaneously believe that this is some 4D chess move from Musk to allow him to cleverly liquidate his Tesla holdings without tanking the stock - and also believe he is too incompetent to make sure he could actually back out of the Twitter deal which he never intended to complete in the first place.
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.