The other piece of the equation is the decision behind financing with debt vs equity. A company may choose whichever financing is 'cheaper' for them. Therefore

The other piece of the equation is the decision behind financing with debt vs equity. A company may choose whichever financing is 'cheaper' for them. Therefore if equity financing were chosen due to it being 'cheaper' then it may be a signal the stock is too high. This kind of reasoning is probaby why the article mentions Musk himself is buying this round of equity - to give shareholders confidence in the stock price.