Punishment? It's negotiation. It's Elon stating that Tesla won't be putting stock options on the table, but a union still could then negotiate - they could pote

Punishment? It's negotiation. It's Elon stating that Tesla won't be putting stock options on the table, but a union still could then negotiate - they could potentially negotiate to refuse to work unless they're getting stock but it sounds like Tesla is drawing the line there because they believe that their stock is valuable and will become much more valuable; employees will have to decide for themselves if they want to risk potentially losing out on getting stocks and weigh if that's valuable enough for them for whatever else the union may or may not be able to negotiate. Arguably, as Elon said, they haven't unionized yet because of that potential loss - but it's not a threat, and arguably the employees are smart enough to decide for themselves.