Could a derivative work of this image be used as a logo for an organization, without violating the terms of the CC-BY-SA-2.5, especially when considering trademark infringement?
A trademark is typically a name, word, phrase, logo, symbol, design, image, or a combination of these elements.
Likewise, under trademark usage,
The owner of a trademark may pursue legal action against trademark infringement. Most countries require formal registration of a trademark as a precondition for pursuing this type of action. The United States, Canada and other countries also recognize common law trademark rights, which means action can be taken to protect an unregistered trademark if it is in use. Still, common law trademarks offer the holder, in general, less legal protection than registered trademarks.
The following image is licensed under a Creative Commons Attribution-Share Alike 2.5 Generic license: