if he was on the board he would be required by law to act in the financial interest of shareholders. He also would be heavily restricted on what he could tweet. That is why he turned the seat down, he couldn't use it as a publicity stunt anymore. If you do any research on how he runs his companies you would quickly see Elon gives no shits about how twitter controls its speech. He has a long history of destroying anyone in his companies that speak out against his visions. He also sues the shit out of anyone that put out bad reviews of his products. Elon is an interesting visionary. but to say he cares about free speech is a lie, he cares about $$$$$ and attention.