You have points there.
The social buttons for GitHub, Twitter, etc. lead to their service with their branding, and there’s merely a place for my branding within their context. The forum icon would take the user to a site with my branding; it just happens to be Discourse Inside.
Indeed, I do not use the WordPress logo for my blog, nor do I see many people who do. (I use The Blog Icon).
A couple non-branded ideas I see say “community”, some of them in a nauseating Kumbaya way. I also see speech bubbles that say “conversation” or “Q&A”, but they feel uninspired.
You did a great job on the logo. It says “discussion”, and it does so in a novel and interesting way. When I put that against the generic speech bubbles, I feel one says “Click me,” and the other says “Ignore me.”
I’m open to suggestions. I’m comfortable using the Discourse logo until an intriguing alternative pops up. (That’s a thinly guised call to readers of this thread to make icons. )