Poison Pills are rarely exercised, this is a positional move. Unlikely Elon is the only interested party at this point. If the board can use a pill to force a slower buy-out discussion and negotiation it is very much beneficial to shareholders.

Their stock price was over $70 in the trailing 12 months.

Even with Elon's offer they are still worth 10 NFL teams combined.

I can find zero credible evidence to support your position. Please short the stock :)