With my thing yes it can be crawled, since requests to /comments/ID will return the JSON comment-data. However there is no enumeration of the valid IDs possible, short of a dictionary attack. (This is where I was thinking that exposing CouchDB might expose more data.)
I did consider not storing emails, and for my use-case that's fine, but I figured sooner or later somebody will want to access them so ruling it out unduly would eventually result in a bug report.