At the current moment in time the Guardians have three players who can man the catcher position in Bo Naylor, David Fry, and Cam Gallagher. The future of the position clearly belongs to the younger Naylor while they have a capable versatile backup in Fry. This leaves Gallagher as the odd man out here.
Gallagher is someone who plays more than he should and is really just complicating things at the current moment for the Guardians. There are players, such as Naylor, who need to find their way to the field more frequently. The presence of players of like Gallagher who should rarely see the field (if ever) is only complicating things. Removing him from the equation seems to be a logical end point here as Cleveland needs to start sorting out who is part of the future and who is clearly not. Gallagher falls in into the latter category and not the former.
This would not be about getting something substantial in return for Gallagher, it would be about freeing up room on the major league roster for others to have their chance. Additionally, having someone who can play multiple positions as the backup in Fry would allow Terry Francona to utilize his full bench through pinch hitting and position changes late in the game.