Texans are making this move because their second round pick - Aireontae Ersery - beat him out for the LT spot and CLE was willing to make the trade since they view Cam Robinson as an upgrade for their starting LT spot.
Will Campbell is justifying the pick by playing well, but I wouldn't use this move as validation of the pick. In fact, it's more accurately used in favor of those who wanted to pass on Campbell if we're being totally honest. CLE is acquiring a player who was available in free agency because they view him as a viable starter and HOU is willing to give him up because they view a guy drafted in the 2nd round as a viable starter. For people who didn't want to invest such a high pick in WC, this is two NFL teams offering validation to the idea of two of the possible lower investment alternatives to fill our need there.