It almost makes sense: With Albert Pujols gone, Lance Berkman starting at first base, and World Series hero Allen Craig injured, the St. Louis Cardinals are in real need of a backup outfielder who can hit—right now, from either of their backup catcher options all the way to potential non-tender Skip Schumaker, everyone on the bench hits like a middle infielder. The recently reinstated Manny Ramirez, regardless of his bizarre pseudo-retirement, can certainly hit. It fits. Almost.
The major issue is Manny-having-been-Manny's steroids suspension, which still applies because of the awkward legal fiction of his retirement; he last played well more than 50 games ago, but because he wasn't on a roster his suspension never began ticking.
It's all a little ridiculous—I liked Dan Szymborski's tweet, which compared the situation to Pete Rose's permanent ban—but them's the rules, and they keep the Cardinals from eying Ramirez as a Craig replacement in April.
Of course, there are other objections—I'm not sure Ramirez, a noted headcase who also played for the 2004 Boston Red Sox, would be welcome in relatively straight-laced St. Louis—but that's the big one.