If you don't like the Twitter/ Facebook reposting, then complain to LiveJournal.
There's an unofficial poll here
If you want to comment on LiveJournal's follow-up Post, go here Many others already have.
ALSO: I snagged this from the very first comment:
'IF YOU HAVE FIREFOX + GREASEMONKEY AND WANT TO GET RID OF THE FACEBOOK/TWITTER CHECKBOXES*
check this out
It's working for all comment boxes now. I think. Please let Livejournal know if you dislike the boxes, even if you install the script. They can't
listen unless you say something, and the more people who say something, the more chance something will change.
* - this will not keep people from tweeting/facebooking comments to your friendslocked entries.'
So,you don't like it, explain that to LiveJournal. That is all.
Actually, that isn't all. I downloaded greasemonkey, then installed DisConnect, checked my comments and tick boxes are all gone, but this will only work with Firefox easily so...yeah. And to be doubly sure, I also did the CSS thing, which is nicely explained here.