Sessions didn't oppose Judge Watson's ruling because Watson is a judge in Hawaii.  Sessions said in the same interview that, "The judges don't get to psychoanalyze the President to see if the order he issues is lawful. It's either lawful or it's not." Sessions opposes the ruling because the ruling ignored the actual words of the order.  
The Justice Department responded to the huhu by saying Sessions' granddaughter was born in Hawaii and the Hawaii was beautiful. The CNN website has the audio of Session's interview.