I hate to say it, but that article is inaccurately reported, and I cringe every time I see it linked. It conflates the PAL codes with the presidential launch codes, which are two distinct layers of security. Even if the PAL is hard coded to all zeros, you still need presidential authorization to initiate the launch procedure.

I thought that was the PAL, not the presidential part.

Basically, engineers added a new layer of security, personnel on the ground promptly found a workaround. Nothing ever changes.