Thanos has to close his fist in order to use the gauntlet or snap his fingers in order to use the gauntlet whereas Manhattan can explode Thanos with a thought
speed of thought >>>>>>> speed of hand
on top of that we know that Thanos is still vulnerable even with the gauntlet because Stormbreaker almost killed him.
and for those saying he could utilize the reality or time stones i ask you haw can he do that if he's instantaneously turned into a blood stain?