I'd think it would be more productive to throw her out the window, or maybe he was going to get more alcohol and decided that stairs were an unnecessary complication.
the alcohol would have made him relaxed so he was probably limp when he landed, which reduces injury when hitting the ground. To the above post, I highly doubt that he rolled as you need good timing to avoid faceplanting or slamming your back on the ground, heavy intoxication would have reduced his timing and coordination quite drastically, although I have never been drunk let alone tried parkour while drunk so I may be wrong, hang on I'll get wasted and let you know.