Leaning toward the trade market rather than free agency is due to a desire to create some roster flexibility that the current group lacks. None of Carlos Estevez, Matt Strahm, John Schreiber, or Bailey Falter can be optioned to Triple-A. Lucas Erceg has a full slate of options but isn't going to be sent down, given his status as one of the team's top bullpen arms. Daniel Lynch IV and offseason signee are the only relievers who could plausibly be optioned right now.
Basically, back in the day, MLB had a problem with some teams signing and stashing guys that could probably be productive major leaguers in their farm system. This was all before the Rule 4 (amateur) draft and stuff like "international amateur free agency" with bonus pools and the like, and basically the idea was that MLB wanted MLB-caliber players in MLB, not waiting in the wings.
The Reds enter this offseason on the heels of a playoff berth that ended almost as quickly as it came, having been swept by the eventual World Series champion Dodgers in two games during the NL Wild Card series. There's still reason for optimism headed into next year thanks to a fantastic rotation led by Hunter Greene and Andrew Abbott, but Cincinnati's offense could clearly use some help.
General manager Mike Hazen recently pushed back on the idea that he might have to subtract some salary via trade, telling Nick Piecoro of the Arizona Republic: "I don't really feel that way, honestly. That's not the impression I have. Are we going to be doing what we did last offseason? Probably not. But I don't think I have zero wiggle room or avenues to pursue players."