Not to mention that this requires a lot of upfront time and capital and depends on no circuit breaker being pulled, which would be quite likely giving the high amount of damage and blatant market manipulation.
"Signs of progress toward a coronavirus vaccine by Moderna propelled most corners of the stock market higher. … Most of the gains followed the release of a new study suggesting Moderna had reached a breakthrough with its coronavirus vaccine, setting the stage for a larger trial at the end of this month. Cruise-ship operators, airliners and other stocks sensitive to the coronavirus crisis led the stock market higher. Shares of Moderna rose $5.18, or 6.9%, to $80.22.
Royal Caribbean Cruises Ltd. was up 21.2%. Norwegian Cruise Line Holdings Ltd. was up 20.7%. Carnival Corp. was up 16.2%. American Airlines Group Inc. was also up 16.2%. United Airlines Holdings was up 14.6%. The biggest gainers were the vaccine-sensitive industries, not Moderna itself."
[1] https://www.bloomberg.com/opinion/articles/2020-07-16/a-vacc...
You could set up a plausible history ahead of time by doing innocent TSLA trades. Maybe establish a pattern of regularly scheduled trades. And then it just so happens that the fake tweet comes out right around when your scheduled trade was going to execute.