Im sorry, but this 420 price is a serious problem. For one, it caps the stock at 420 from my point of view. The reason is that many funds will have to exit the stock before the deal is completed or wait until the deal is done at sell at 420, they will want to exit at the highest price so every time the stock goes above 420, it makes more sense to sell at that point rather then to wait for the deal to close. This is enough supply to cap the squeeze at just over 420. The deal must happen to force covering, otherwise they just wont cover.
Because the 420 is a cap, the shorts have a known loss that is 10% higher then today's price. They can short at will have almost no downside beyond the 10%. Clearly today's price action shows that shorts could get out at anytime.
Here is the worst part. Because the price is capped at 420, everyone who had long dated calls are crapped out. They are going to 0. As they go to 0, shorts can buy these calls for Squeeze insurance. They have already dropped to 1/4 the value before the stock was halted. What does this mean? If there is a squeeze, shorts can cash in the calls and clean house. If the deal fails to go through, they can also profit from the calls because they will return to normal values. If the stock price collapses because it turns out Elon never had any real funding, then they are going to clean house on the short position. Elon has basically gifted Shorts an out while screwing anyone who was long with calls.
If there is a squeeze, the shorts can sell the calls they bought for pennies on the dollar.
If there is no squeeze and the deal goes through, they can cover and the funds will bail them out.
If there is no deal and the stock stays elevated, then the shorts can add to their short and mop up profits on the calls as they return to normal.
If the SEC finds an issue with the announcements or there is an issue with the funding, shorts will get bailed out by the stock price dropping to 200.
I dont know what Elon was thinking, but this is absolutely terrible for anyone who was long Tesla with options and a complete bailout for shorts smart enough to buy insurance.