Its not a pen though, as the original 'foul' was Silva. So if Oliver blows for a pen and its reviewed by VAR, its not a pen as the offence (assist, if you like) was by Silva. It that ball passes by Alexander and Sterling slots it, its no goal as its handball. I don't need to check any rules to know that the original offense was Silvas, and City would have gained an advantage from a handball, intentional or not. As I say, the argument then becomes whether to disallow the goal and it should have been chalked off but it's not a pen. I suggest you check the rules.