I had a Captain 'teach' me that setting LO initially, then waiting for the decel light and selecting MED gave a much smoother and generally better roll-out than manual brakes or selecting MED to start with. He would reach across and select MED a few secs after landing (still doing lotsofknots!)
I did NOT appreciate...
a) him sticking his head in to find a non-essential pb at a particularly eventful stage of flight
b) as you say, the possibility of him selecting the wrong switch and hitting MAX
Also had another LHS select MAX instead of BRK FAN as we were vacating with the spoilers still extended - PAX did not enjoy..
Worse still the cabin crew told frightened pax that F/O had probably just missed the turning and had to brake hard! B*stards!
Now I do NOT delay before disarming spoilers, don't look forward to inspecting PFD that closely again