Solution
Would it have solved the hacker issue if he just avoided wireless connection, turned his wireless modem off and connected his laptop by means a physical network cable?
Also: resetting the modem and reinstalling a firewall and password is always possible if you can connect to the modem directly, right? By doing so he could have stopped the hacker from accessing.
And I'm fully aware that the film tries to go deeper than the anekdote of a guy who gets hacked. But it's hard to look beyond that if the audience is preoccupied with questions like mine above.