i think if you hav been around abuse, then him spreading his legs is a normal thing for you to notice and think about. personally, that would be so distracting and bothering to me. i would probably not get very far because i wouldnt' be able to stop focusing on that. i think if it bothers you, you might want to talk to him about it. let him know that it makes you uncomfortable, and why, and i think he would be more than happy to talk about it with you, and maybe change his position