"the use of an unauthorized device in connection with your Nintendo 3DS System, will render the system permanently unplayable."
You can't say they didn't warn you.
Also
"You may not publish, copy, modify, reverse engineer, lease, rent, decompile, or disassemble any portion of the Software, or bypass, modify, defeat, tamper with, or circumvent any of the functions or protections of your Nintendo 3DS, unless otherwise permitted by law."
Legal homebrew confirmed.
Source: 3DS EULA, Section 1 http://www.nintendo.com/consumer/info/en_na/docs.jsp
I mean GW and Nintendo/Sony are 2 different groups, one makes console gaming/media corp and the other just tries to utilize the hardware in a manner that is deamed illegal. The illegal part can vary by country, but to most its illegal.