I guess, though it's not like anyone with access to the entry couldn't write something new about it elsewhere anyway. But yeah, you wouldn't want to do it by accident. It seems to me like actually wanting to broadcast a *comment* is a rare enough thing that the options there ought to be tucked away in a drop-down or something; better UI design regardless of the privacy issues anyway. I can see them much more commonly being used to broadcast original posts, so I don't really mind them there.

Though it only makes sense for them to show up if you've already linked/authorized LJ to post to your twitter and/or facebook. Do the boxes appear even if you haven't? If so, that's just kind of dumb.