Even if everything you say is true (and the idea that Solar City had any kind of workable tech with the solar tiles at the time of the acquisition is very flims

Even if everything you say is true (and the idea that Solar City had any kind of workable tech with the solar tiles at the time of the acquisition is very flimsy), the fact is that if Solar City was insolvent, and Elon Musk knew that before the purchase was consummated, then he violated his fiduciary duty to Tesla shareholders to secure the best deal. Solar City could have been picked up for a song and its liabilities (which are currently a huge anchor on Tesla's balance sheet) restructured.