Signing Jose Iglesias would be asking for drama, as Cardinals fans would likely complain about them "signing a shortstop, just not the right one". In the case of Iglesias though, he would be valuable insurance in the infield for St. Louis, especially if Paul DeJong does not turn things around, injuries pile up among their infielders.
In 2022, Iglesias slashed .292/.328/.380 with 3 HR and 47 RBI while playing very good defense at shortstop. He's a guy the Cardinals could use at third base and second base as well, should they end up needing to. Right now, Brendan Donovan seems to be the guy that would plug and play at any position should they need him to, but since they expect him to play every day, they need a reliable backup option as well.
The Cardinals front office has liked what they have seen from DeJong this off-season, and Derrick Goold recently captured some of the changes DeJong made to his swing. If his commitment to changing really works, Igelesis would not be needed on the roster. But if the Cardinals' coaching staff is skeptical that DeJong can make an impact this season, then bringing in Igelesis seems like a great solution.