Whether one considers it r34 or not, there are no nipples showing, no genitals/butthole (or their bulges) showing, no genital secretions showing, and no unambiguous sex taking place. So, you're totally in the clear.
If you do
want to post full-out porn, there's a system for 'Mature' tagged threads, which are only seen by users who've opted in. See the 'settings' link in the upper-right corner, and this thread for details.http://mlpchan.net/site/res/3678.html