Most likely they simply didn’t want to being up Hamilton to bench him. But let’s not overreact to the Dalbec/SS situation. After it is entirely possible that even though some fans and John Tomase are not wild about Dalbec at SS, that maybe the Sox saw something in the 67 innings (counting 45 MiLB) in which Dalbec has played SS. Maybe they even looked beyond both errors.
If Hamilton’s weak defense was part of why he wasn’t promoted, that’s independent of Dalbec’s promotion. Not like any of us know whether or not Hamilton is even an upgrade at SS over Dalbec…