I think one of the main reasons people re-upload to imgur is it has more reliable bandwidth. It's less likely that your blog could handle the massive amounts of redditors going to view the site and there's no way of knowing that when uploading a photo.

That and imgur is more likely to be around long term so 6 months from now if someone happens to come across this, it would still be here, it may be less likely for your site.

Edit (not really): It looks like he didn't even upload it to imgur he just direct linked to the image on your tumblr, which is kind of douche.

The other thing is there seems to be a split consensus. A lot of people seem to hate when people link to site wrappers (specifically for things like youtube or vemo videos) so it's hard to tell if something is genuine content for a given site or if that site/blog/tumblr is just a wrapper to get views for content someone else has created.

All that being said, I genuinely laughed at this so if you did make it keep up the good work.