He's not good enough to merit a place in their starting 11, but they have enough games against creampuffs that they can afford to play him a bit. Sucks for the good players they have that are already struggling for playing time, the squad is absolutely stacked. Pastore, Menez, Lucas hating this news.
I'm sure Beckham was offered a contract at PSG for commercial purposes. Competition on the right flank is huge. He'll be "serving" a few minutes per game probably.