I fail to see how life in deep space + life on earth < life in deep space, especially considering that V. is super against dying.
It depends on how things work, of course, but the danger is that he will be stuck in an incorporeal form on Earth forever. When canon!Voldemort is flitting about in Books 1–4, possessing Quirrel's head, drinking unicorn blood, a little baby cuddled in Wormtail's arms, it's not clear that he's in a form that can be killed at all, but it's not a form that he appreciates either. So it may be that the only way to sail the stars on Pioneer is to get a body to be killed in (and I don't know whether MoR!Quirrel's will do or he needs to be resurrected as at the ...
Update: This post has also been superseded - new comments belong in the latest thread.
The second thread has now also exceeded 500 comments, so after 42 chapters of MoR it's time for a new thread.
From the first thread: