Proper nouns are proper nouns. I think that ultimately, these should be fixed in the same manner as addressing any other form of capitalization that is needed when dealing with someone who is unfamiliar with the given material. I think it's fair that we can treat these no less than we treat any other form of capitalization fixes.
In general, capitalization falls under the same point as spelling and punctuation - don't go out of your way especially if there isn't a lot to fix. If there's a lot to be fixed in the post, or if there is a particularly egregious issue that must be fixed, then it is probably more warranted to step in with editing.
If there is only one or two instances in the post, and nothing else to fix, it may be helpful to make a polite and helpful nudge in the comments, reminding the author that it is a proper noun.