Okay, who would really ignore Sam. Really?
I know that people complain that she is the manic pixie dream girl but I don't think she is. She's just a cool girl with stuff going on.
And to be totally honest if someone that looks like Sam and is that cool and likeable and fun, why the hell would Large (even in the state he is in) make his moves to shun her in the doctors office?
She is amazing and it makes no sense that he wouldn't be over the moon that she was showing interest in him.