To be fair, the only reason this info is public is the person is 'tagging' the activity. By default all tagged links in delicious are public and that makes sense. If you tag an activity like this on fitbit, you should mark it private.

I have a fitbit and I can't for the life of me figure out why people would start tagging every activity they do and start and end times... but if they are adding tags, comments, and other personal details they should mark it all private.