They are excluding all users who can’t get Discord accounts, such as those who can’t agree to the Discord TOS, for example. Free software projects and other public benefit groups should not be discriminatory.
They’re also banning political cartoons within their group’s communications, by implicit inclusion of the Discord TOS which bans several common, normal, reasonable types of communication.
I’m a paying member of a local nonprofit organization; they use Discord exclusively to communicate. I am excluded from all of the discussions as a result of my not being able to safely get a Discord account. That’s discrimination whether you like to acknowledge it or not.
The presence or absence of threats against one’s person does not legitimize or delegitimize their insistence upon personal privacy.
The difference, in this case is that you're not being forced out of participating in conversations because you're, let's say, black. Instead, you, on your own, are opting out of communication channels because of your own beliefs.
We’re way down in the weeds here. If you’d like to continue this discussion further, please just email me.
You don't agree with Discord's practices and lack of privacy, something which, by the way, I agree with you, and as such, decide not to use it. They are not discriminating against you, you're the one deciding not to use their service. To me, it sounds the same as if you don't like McDonalds because it's unhealthy, then accuse them of discriminating against you because they won't serve you some lean chicken salad.