It means a standard passcode:
From the 2nd link: "The researchers said that all the user needs to do to start the attack is enter their passcode - they pointed out that this is a pattern of ordinary use, such as to check a message while the phone is charging.
As I read in the end of the article from your first link, I think it is better to rely with our own charging equipment... :think:
For example solar-powered! :lol:
Do public charging stations have a great demand? I'm not sure, but there are certain places where they're common - for example on airports...