Very interesting, from the screenshot of the HTML, I too would not expect to see these hyperlinked. For clarification, you mention this is only occurring through the API?
If so, there might be a bug at play here. As such I would recommend submitting a case in your secret customer group here in the Jive Community so that the next available support engineer can assist with further investigations. When creating the case if you could include the following it should assist them:
1. The specific API call you are making
2. A link to where in your Jive instance you are seeing this behavior
3. A copy, or link to where the original text you are using can be found
OK, will do that.