I used to work in the automotive industry. It is common to push suppliers for price reductions on existing and future agreements. But I have never heard of partial refunds on past sales. This is not a smart game of chicken to play. If your suppliers don't think you are able to meet your obligations, they will rapidly cut you off from all credit (if not stop doing business with you all together). And if suppliers require upfront cash for parts deliveries then Tesla is in big trouble due to their high negative cashflow.

Also, a move like this could trigger additional credit downgrades. Institutional investors (the main holders of Tesla stock) are much more likely to dump the stock if ratings agencies further downgrade Tesla's creditworthiness. I'd be surprised if Tesla were bluffing here- I think this is either pure desperation or "fake news".