As mentioned before, naturopathy is an umbrella term that includes several non-science based approaches to medicine, including homeopathy. While I imagine (or hope) that his address at the convention had his usual environmental thrust (I haven't been able to track down a copy online), having a famous and respected scientist and environmentalist speak lends credibility to naturopathy and its pseudoscience. It's a great marketing move by OAND. Not such a great move by Dr. Suzuki. This is not unlike earlier this year when UofT and the SickKids Foundation appeared on a brochure for a conference put on by an anti-vaccine group.
I understand the importance of getting his message out to a wider audience though strangely the poster doesn't include the title of his talk, "The Challenge of the 21st Century: Setting the Bottom Line." Instead Dr. Suzuki is attached to the message, "naturopathic doctors are getting to the root of it," and this will be the take home message for many people. For better or for worse.