Quote from EnzerDeLeo
Edit: I had a much larger post here regarding this issue, but I am going to replace it with clarification I got after the matter.
"User vs provider.
MCedit uses Pygame, it does not provide code to Pygame that would create the "down stream cascade" link necessitating handoff of rights.
Same with Bukkit and Worldpainter with GSON, SQLite, MySQL, SnakeYAML, and Install4J.
Remember, cascades go down, not up."
These projects all distribute compiled code of their libraries, as opposed to source code. If that's acceptable, then so is my dungeon-generating library: its compiled code would be distributed with the plugins/mods which use it, but I retain the rights to the library itself. Good for me.
That also debunks an earlier claim that "all Forge mods and Bukkit plugins derive from Forge/Bukkit, which in turn derive from Minecraft, and thus all of them are derived from Minecraft". Forge mods and Bukkit plugins don't include/provide Forge and Bukkit - they merely use it. They actually don't even contain the compiled code. At that point, the only thing that lets the argument "Mojang owns the rights to mods/plugins" stand is the "content available through Minecraft" part of the EULA.
That, in turn, leaves me asking how far "content available through Minecraft" goes. Is a private, in-house server plugin available through Minecraft if the server itself is publicly available? According to your quote, it doesn't apply to libraries used by mods - but the general consensus here is that it does apply to mods used by other mods (mod loaders and APIs)?
As for cascades going down and not up - I suppose cascade was a poor choice of word. There is an "up", however: it comes from systems like Forge making mods available to Minecraft when they otherwise would not be. The mod itself is not available through Minecraft until Forge acts as the bridge, just as my dungeon library would not be available until connected via a mod/plugin. The "up" which propagates is not copyright or derivation, but rather the obligations described in the EULA: if all dependencies do not comply with the EULA, the content as a whole cannot comply. And that (combined with the "all content must be your own work" clause) is what puts MCedit, Bukkit, and WorldPainter in the gray area.
Anyways, as you suggested before your edit (at least, I think it was you), I've sent an e-mail to Customer Support regarding Mojang's meaning of "content" and interpretation of what the EULA means for projects making use of libraries. Given Grum's recent posts on Reddit, however, it would appear that the entire "Content" section has nothing to do with mods and tools at all, and the EULA thus has zero consequence on libraries and copyright.
Quote from EnzerDeLeo
I'm sorry, but you cannot infringe on my protected right to free speech to spread the information Mojang has presented.
Free speech is a liberty, not a claim right. It protects you from having others stifle your speech; it does not actually require anybody to listen. Sorry to be blunt, but implying Stratagerm's words interfere with your own right to free speech is absurd: he's well within his own right to free speech to say he doesn't want to hear something from you. Nothing personal; I just hate it when people try to use "right to free speech" as an obligation in internet arguments like that.