if a component melts in a tent how would you expect it to fare on a car, that sits outside in the sun all day rather often? around parts that often generate a lot of heat.
Are you saying that things can be manufactured in the same environment where they'll be used?
Even if all the parts are OK one would think not the whole manufacturing is temperature-insensitive.
I wouldn't worry if I saw Tesla as a responsible company, but I see them as desperate to achieve goals and capable of misleading people (e.g. autopilot being marketed as much more than what it currently is [1]).
They're being assembled. It's not like they're doing injection moulding or wave soldering circuit boards in open air. They have preassembled components that they're putting together.
The only thing I would be concerned about is dust or moisture intrusion.