as long as he is giving the muscle tension then different strokes for diff folks
lets remember what we want to accomplish when we workout.
in no particular order the main things we want are
1. shuttling in nutrients, oxygen etc into the muscle ie: 'the pump' .. yes the pump is a good thing
2. breaking up muscle fibers
3. rest, rest, rest
4. whole foods, carbs, cals, protein, nutrients, minerals. not gonna grow eating fruity pebbles and hot dogs.
5. releasing/activating hormones in the body
if he is creating a blood rush into the muscles, releasing hormones and breaking up the muscle fibers and doing 3 and 4 as well then hence why he is so huge. the key thing though that is a negative to 'poor form' is the injury factor which will eventually come back to bite you. hence why i tell guys to avoid the smith machine and if it hurts then dont do it. a lot of guys try to do too much weight so they end up lifting with their tendons/ligaments and not their muscles. this is counter productive