He refuses being bottom, but he says he likes only top guys....

[Chris]

Among many gay people there is a concept that so called top should be more masculine and dominate over sensitive bottom. It's a very old concept. It originates even in Roman Empire where bottoms were usually young guys, slaves and basically people of a lower category. Surprisingly, Romans had different view on gender then modern societies. For them a man active in sex, no matter if gay or straight was regarded as one gender, while woman and a submissive man, another one. Maybe such a way of thinking is written in our genes. Maybe he thinks you're not masculine enough or as masculine as him or you're younger. That would explain why he describes himself as bottom in conversations with older men.