As stated in the opening post: 'all hands'.
That eliminates #1 (not all employees or even half of employees of Tesla are 'sales' people or 'front' people).
This has the most possibility of your options, though again, not all employees are 'public facing'. The results of the investigation could just as easily be sent via interoffice e-mail. Needing to call an all hands for this doesn't ring right, unless it's really bad news.
#3 Um...no.
#4, again can easily be done via e-mail and doesn't concern many beyond the paint/sales departments.
All hands meetings that I've ever attended are generally to a) rally the troops, or b) assuage rumors, rumblings or other news that ripples through companies and has a negative effect on productivity - like a media rumor that the company is heading for bankruptcy/will be laying people off - nipping it in the bud, as it were, or c) give a general overview of the direction the company is taking in the near future.