Did he though?

He can't very well carry Annie back, because by this point the lad has gone full Black Knight, he thinks 'tis but a scratch, he'll bite your legs off. No way is Obi-Wan going to parkour his way across the lava flats back to the facility, find his way back to the landing deck from outside (maybe easy, maybe not), get on the ship and get out of there, all while hauling a snarling, screaming, wriggling, rabid torso that can also use the Force.

He could certainly have killed Anakin, but he didn't have it in him now that the fire of battle has gone out and Annie's a lump of burnt jerky. He might have rigged up some kinda hover-platform, if he could get one of those droids, but probably not. And he's not going to Force-float a combative Force-user across a half-mile of rough terrain (for the most part, no Jedi ever uses telekinesis for more than a brief moment).