No I'm not. Both have the same free speech. Except the corporations speech is being restricted by the government while the user's speech is being restricted by a private corporation. Only one of those is a First Amendment issue.

>We already have tons of laws that restrict what businesses can do, that would obviously restrict speech - like banning discrimination.

Discrimination is usually action and not speech. It is someone being fired, promoted, not hired, or just generally being treated differently. It generally takes for discriminatory speech to venture into harassment or a hostile environment before the government would step in.

>The law does not, in fact, dictate what private businesses can say. It gives them a list of things they cannot say

How are these not the same thing? Telling someone they can't do something is inherently telling them what they can do.