You thought he looked good? He had a 54% completion percentage, no TD's, lost 2 fumbles and threw an INT, and he was playing against several backups. At best I'd give him a "we'll see next year," but that was FAR from a "good" performance.
And the Chargers are more "screwed" because there's NO way Brees is coming back quickly from that injury, and since he's an UFA at the end of the year, they will be faced with a tough decision on how to keep him, or if they WILL keep him or not. And the performance today by Rivers can't give them any comfort, knowing that he didn't show much, won't get them what they want in a trade now, AND he might be their only option.