Is there any reason given why Q...
Wouldn't transport them back to earth or why Janeway wouldn't ask that of Q since she is his son's godmother
"At the end of life, we will be judged by love" ST John of the Cross
For reasons beyond the comprehension of mere mortals.
Q doesn't like to help. He likes to toy. He's also a strong believer in races overcoming adversity on their own in order to make them stronger or smarter.
I think Janeway did ask him, but he just grinned and vanished. Might be wrong, but that may have happened in the episode where the crew helps end the Continuum Civil War.