can someone get pregnant like this???

Ok, so Im posting this for my cousin since he's so worried. Around a month ago, he said he had woken up like around 5:30 and started masturbating. he said he kept going on and off with it until he came around 6:10-6:15 something like that. some semen got on his hand so he wiped it off. then he went back to sleep. later he said he got woken up by his sister, who is twelve and she asked him to button her jean jackets wrist buttons, (like to put the wrist part together. him being tired, he did it and buttoned it for her. then he said that's when he realized he hadn't washed his hands yet. now he said they weren't like wet or had liquid on them, they just felt funny because he had the semen on him previously and he just wiped it off. so he went to wash his hands and then his sister was brushing her hair. so he said, "hey let me polish those wrist buttons" and he took his bottom part of his shirt and her wrist and "polished" the buttons. he took a few wipes with the shirt and then did the same with the other button. then she left for school. so basically he's wondering if she can get pregnant from the wrist buttons he touched? please give a response, he's really worried and it's messing with him. also he said that she doesn't get her periods yet (he asked her)