That... is not what that nickname means, at all. It implies that they're innocent/ "healing-type"/ caring/ sweet etc.
It's a little bit of both. The original meme is an Onion headline - "Beautiful Cinnamon Roll Too Good For This World, Too Pure" - and although it does mean that the entity described is sweet, innocent, and so forth, it also implies that the Break The Cutie trope is likely to ensue, because inflicting suffering on a true innocent is a cheap way to generate angst.
Mind you, I have seen "cinnamon roll" used merely to describe someone who's impossibly innocent, without the implied doom. So I would say that it could be used either way.
