If you're thinking that because Atlas does gateway travel (not home basing...there's a difference) you'll have more time at home with your wife, you're making a bad assumption. You still might have to commute, you'll just be doing it on Atlas' terms.
As for the Union, I wouldn't worry about that too much. There's a lot of hard-line union propaganda out there and you have to balance that against a company that is hell bent on sticking it to the pilot group. Nobody from the Union is out there threatening new hires, but they are aggressively trying to dissuade anyone from working for Atlas.
If you want the job because you think you'll enjoy the work you'll do, that's one thing. If you want it because you think it will make your life easier with your wife's condition, I strongly urge you to look elsewhere.