It
validates if I remove the encryption.xml file (it seems to be a bug in epubcheck), and it loads into Bookworm if I add a title and replace %20 with a space in both content.opf and toc.ncx (that could be a bug in Bookworm, but I don't know if the %20 encoding is allowed in opf and ncx files).
I'd say the %20 issue is either a bug in InDesign or a bug in Bookworm/Stanza.