1. It never claims to sync your Firefox bookmarks. It helps you to create another list of bookmarks that you can sync using your Google account. There is a misunderstanding of the term "bookmarks".
2. The request of permission for ALLIZOM.org is because it is a Mozilla Firefox extension, and it ask for permission to save the bookmarks data in your Google Drive app data folder. (Another Firefox extension developer who use Google API can verify this.)
3. I'm not sure why do you have issue on that.

However, I should say that currently I do not have time to update this extension. Since there seems to be some updates from Google API and Firefox extension API, I don't yet have time to update my extension.