It does look odd! Because the submission page is a Hacker News page, I can not control its behavior. One of the things I would like to do, after being convinced that the HN community wants this feature, is to discuss possible options with the YCombinator folks.
I thought you mentioned you were using the HN API? Even without it, can't you use something like `curl` to make the post and perhaps some gross regex to strip away the bits you want and load it into your own domain space?
That would work if I were to submit from a single account but not to submit on your behalf.