Not to have him cancelled in the first place. No need to pretend that doing something under the mob pressure is the same as doing something entirely willingly
Far, far more people have protested the positions of power held by (for example) Joe Rogan and Dave Chappelle. They ignored the cancellation attempts, and they're richer and more influential today than they were a few years ago.
"Cancellation" is a state of being famous enough that your controversial beliefs upset a large, loud number of people. In Eich's case, it threatened to have no effect on his career. He chose to change his career because of it.
Eich expressed his First Amendment rights, and other people expressed theirs in return. Why should either of them give up those rights for fear of offending the other?
No one forced him to do anything, and Mozilla itself certainly didn't force him out.
His free speech was met with the free speech of others, and he decided it was too painful to stay in that spotlight.
How would you prefer it to have gone?