Valve specifically drew Nintendo's attention to the presence of Dolphin Emulator on Steam
gagadget.com
I'm sure you've already heard that Nintendo has blocked Dolphin Emulator on Steam, allegedly because of the DMCA, but as it turns out, this is not the whole story. According to The Verge, which was provided by the Dolphin development team, Valve helped Nintendo draw attention to the Wii and GameCube emulator on Steam and unilaterally blocked it without even giving Dolphin developers a chance to defend themselves.

The plot continues to thicken over this. I don’t believe emulation should be considered illegal. The only illegal part is how you get the ROMs. Another friend mentioned to me the part that burns him is that Nintendo has been sitting on GameCube and hasn’t done anything with it since the Wii Virtual Console!