I think 3rd party hosting is also against the rules with imgur, so while it might work now... there's a good chance they'll kill the functionality at some point in the future like Photobucket did.

I'd been using Photobucket for forum photos for over 10 years and they shut my account down a few weeks ago.  I'd be willing to pay $10-$20 monthly to keep the photo content alive, but $39 per month seems like too much.