Lol its like telling a middle aged lady that shes too old for a plastic surgery. Who cares. If u wanna play then you gotta play before u die and regret your decision for not playing.
Ask them to provide written evidence from an official source that clearly states the maximum age you are allowed to be a fan of pokemon. When they say they don't have one, mock them and their lack of legal understanding, bemoan them for speaking slanderous lies and tell them that in future maybe they should get their facts straight before they tell other people what they should and shouldn't be doing.