It depends. If they were violating an existing corporate policy and got fired, there won’t be any problems for the company. Likewise if they were recording meetings with participants in California or one of the other states which require all parties to consent to recordings as those are explicitly crimes and Tesla could have the employees charged.

If the policy didn’t already exist there might be problems. You have to be squeaky clean in order to defend your job while trying to unionize in a company unfriendly to the idea.