Keep Keith down so he can maintain his rookie eligibility next year and be eligible to net a PPI pick if he really takes off in the bigs. He'll be a consensus Top 100 prospect.
Also, I haven't looked ahead yet and don't really anticipate any 40 man crunch, but if you foresee one over the offseason, adding Malloy and Keith now could have some implications. This is likely only an issue if you add a bunch of prospects close to the Majors at the deadline. Malloy and Keith don't need to be added until after the 2024 season.
Anyways, all we see are the box scores. For all we know he's working on something specific in Erie and will be moved up once that box is checked. There's no rush.