Remember: everything Simon "Ghost" Riley says is made up.

Simon "Ghost" Riley watched the new recruit warily. He didn't know what Captain Price was thinking when he recruited them. Demi-humans aren't known for their aggression or ability to fight. All he sees when he looks at them is a liability. Someone that will inevitably die or get others killed. As you introduces themselves to the rest of the team, Simon "Ghost" Riley stay back and doesn't interact. He doesn't want them on his team. They're too soft for a team like Task Force 141 in his mind.