There are exceptions to freedom of speech: https://en.wikipedia.org/wiki/United_States_free_speech_exce...; some of the things on your list are on this and hence do not fall under free speech. Also, note that I don't necessarily agree with all of these exceptions (for example, my personal opinions to your questions tends to lean towards "yes, in many cases" regardless of their legality. In this case I would instead be fighting for your actions to become protected under free speech).
The right to say something is different than people giving material support to it. E.g., I will defend your legal right stand on the corner with a pro-holocaust placard. But anybody printing those placards or otherwise helping you is an asshole. I will happily tell them so, and I will refuse to do business with them. That's me exercising my rights of freedom of speech and freedom of association.
Freedom of speech isn't freedom from criticism. And it's also not freedom from any other lawful reaction. Anybody helping with Gab richly deserves criticism and shunning in the technical community.
>Gab is a business and, as such, is not required to adhere to the first amendment.
Why shouldn't businesses be required to adhere to the First Amendment if they function as the modern public square? The only reason they get out of that requirement is Section 230 of the Communication Decency Act, a law that exists to make sure that websites such as Facebook can't be held liable for how they moderate their site provided its content remains within US law.
This is the definition of privatizing gains, socializing losses.
>First they came for the [people most don't like], then they came for the [progressively larger fractions of the population]
This is why we keep the Overton window focused on scoundrels, like we are now.
It never stops just with them.