Yes for now it is, but when I finish releasing a stable 0.4.5 for Fremantle I plan to port it back to Diablo or even earlier.

The step to save to PDF before sending it is needed because once I create, let's say, a temporary PDF that I then give to the sharing plugin or e-mail or bluetooth system to send, then I do not have any control of it anymore.
Xournal has no way, that I know of, to know when the sending is done and, thus, when I have to delete the temporary file.

So I'd rather ask you to save it (as if it was going to be exported to PDF) than have temporary files lying around the system.

Until, of course, I, or someone, come up with a better idea...