I am not sure where you are from - France, judging by the hour, grammar, punctuation? - but after living outside the US and having the luxury of observing my home country from the outside, I have found that free speech is not treated with as much value as we seem to claim. Some would say that free speech in the US is very much threatened nowadays.
Free speech does not, however, protect you from dealing with the consequences of your speech.
It is NOT the freedom to force others not to listen to or act on what you say. I cannot for the life of me figure out why so many people misunderstand this.
Actions have consequences, and this includes speech. It is not the job of any American to support thouse who espouse beliefs they find repugnant, just because they have the freedom to speak up about those same beliefs.
The consequences of this were a man losing his job and a big backlash.
This made it difficult for her to do her job effectively, lowering her value to her company to zero (and probably a large negative).
I don't see that SendGrid was acting to suppress her free speech. Instead, they were writing down an asset that had declined radically in value.
Getting involved between private parties is generally not productive in the long run, as it necessarily provides the government more control over speech. Private business may abuse civil rights from time to time, but the government has far more potential (and historic precedence) for abuse.