I don't condone (or weigh in either way really, the convo is interesting) Walt Jr. siding with his mom/calling the police on his pops but it's not as if he had any time to process anything he was being told.
Marie: "Your dad is a ruthless drug lord"
Walt Jr:
Marie: "The male role model in your life, Hank, arrested your dad".
Walt Jr:
Skyler: "Ok, let's go home"
*get home, Walt is packing*
Walt: "We need to leave right now!"
Skyler: "You killed Hank!"
Walt Jr:
And that's all before they starting the knife fight. He got hit with every major plot point of the show in literally 15 minutes.
Fred.