It's a realtively small sample size. He's never played a full season. He was over .300 in the minors and the year he had the most ABs in the majors was last season and I'm convinced that he just never recovered full from his injury (where he was hitting .320 prior to be injured).
I'm not advocating Keppinger be a starter, but I think as a spot starter in the IF, he's a good guy to have around, particularly as you said, against LHP.
If the Reds had better options, I'd be all for them kicking Keppinger out, but I don't think, as it currently stands, that Keppinger ISN'T one of the 25 better options, even if he is on the closer side of 25.