I would have thought that it's not easy to just "let go" employees in Australia under the Fair Work Act etc.
If these are genuine redundancies (i.e. the entire SC division is no longer part of Tesla’s business and will remain so) then yes, people can be let go immediately provided all contractual employment obligations are paid out (notice periods, redundancy payments, leave and super entitlements etc).
The problem this might create is if Elon or the Board realizes the stupidity of what he’s just done, and reverses the decision and then tries to rebuild a SC team again. The original mass-sackings could very well then be construed under the Fair Work Act to have been a ruse to bypass employment law and simply get rid of people “at will” which is not permitted here. And that could open the door to unfair dismissal claims.
Businesses can’t make a whole bunch of roles “redundant” and then a couple of months later re-create those roles with slightly different names and then hire new people into them. The original “redundancies” are very unlikely to be considered “genuine” in that case.