It's not really a big deal in the 757 and having thousands of hours in planes without autothrottles, I wouldn't have even stopped the climb. Plan to continue assuming the FO is comfortable and try to troubleshoot with mx control to see if we can get them back for convenience.

But, if he was not comfortable, i can see that POV, just skip the cringe conversation over the radio, tell them you're going back, land, and worry about it on the ground.