That's because the left have so far failed to exert their influence on SpaceX like they have other companies. I can cite plenty of other cases where a tiny minority of leftists pulled a similar stunt on or at a different company and succeeded in their objectives.

Here's a fun one: https://winteryknight.com/2020/11/16/target-bans-book-critic...

"An official Target company Twitter account announced Thursday they had removed author Abigail Shrier’s book, “Irreversible Damage: The Transgender Craze Seducing Our Daughters” from the retailer’s “assortment” after an unverified Twitter user complained the book questions transgender ideology, especially the concept of irreversible hormonal and surgical experimentation on minors."

This article is proof that non-leftists are firing people. If the goal is to stop people being fired for speech, then we shouldn't be focusing purely on leftists, but on all sides.