He'll need a computer to get access to his device again.
Here's what he could try first:
http://support.apple.com/kb/ht1212
If he had Find my iPad enabled in iCloud, he'll have to remove his device from there first, also through a computer. The instructions should be in that link as well.
He also could try to restore his iPad:
http://support.apple.com/kb/ht1414
A computer is needed here as well.
Reading your post once more, I'm somewhat surprised that the password screen appeared, although you didn't enable passcode lock. When he doesn't have to enter a passcode, the only way to get access to the device should be to slide to unlock, nothing else.
Just in case you/he didn't do it already: perform a reset (press and hold Home and Power button at the same time until the Apple logo appears, then release both and let the iPad power up). It's also recommended after an update.