The Twins have an unhealthy love for veterans, which is why they always rely on them early. Garza, Perkins, Slowey, Baker, Swarzak all are better options than Ponson, and one of them will take Ponson's spot sooner or later.
It seems to me that there's quite a few veteran pitchers who probably shouldn't be playing at the MLB level. I mean, how much worse would a callup from AAA do? And how much cheaper would it be for the MLB teams to bring up a minor leaguer and pay them the league minimum rather than give contracts to guys like Ponson.