This deal has been on the cards for some time now. It was a case of merge or have both carriers beat each other to death.
As the acquiring company, ATLAS' work practices would be paramount, I'd assume ... and that would include the non-ALPA situation!
However, moving out of one's core competency (ACMI leases in the case of ATLAS) is never a really great idea ... especially bearing in mind that Polar's loads have been well down over the last few months.
I think this will be interesting!