I'm not saying this guy is cheating. I'm saying that when cheats are used that is their main purpose.
Do some research on cheats -- they are very advanced. There are some good demos on YouTube where guys break down how the cheats work. You can customise their settings to where they will not actually lock onto people but only go towards and near where someone is. Their lock speed, activation area, lock area, and more can all be programmed. Someone who is good at using the cheats and has their settings configured properly can easily hide that they are cheating.