I see what you mean with giving equal weight to all rights, but there are implementation differences. To not discriminate, you’re restricting an action that might be taken. That does not incur cost or new effort. To facilitate speech, you’re compelling an action to happen that someone may not want to do, especially one that doesn’t provide any benefit to them and may incur additional costs.

The right of free expression is guaranteed by the first amendment by restricting the government from infringing upon your right. It doesn’t say the government or anyone else has to give you a microphone.