He's not the only one surprised. The Master is furious. How dare the Doctor even think to do something like this! He didn't have that right!

He does keep the Doctor from falling, but it's a rough grip, his hands digging into the skin of the Doctor's shoulders (and yes, though wound on one of them). He shakes him, as if that would help matters, but in some twisted way it makes the Master feel better. That's what matters, right? Feeling good.

But no, no, no! This is wrong! He has plans! He's almost done! His signal is almost ready, everything's almost in place! "You're not going to ruin this!" The Master yells at him. "You can't! This goes my way!"