They did, under the condition that "above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software."

They did, under the condition that "above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software." If oh-my-fish didn't include the copyright notice and permission notice for wahoo's code they were using, then this is a valid use of the DMCA. MIT doesn't mean you're free to use with abandon. You still have to credit and provide the license.