WTF.
What some male person has told you about their ludicrous claim that they have 'more experience' of being a woman, is fucking irrelevant to the discussion about sport.
And FFS. Why would you listen to such a ludicrous claim in the first place?
No male can ever experience life as a woman. They can only ever experience life as a male who believes they are a woman.
Even when they 'act' like a woman, they are acting as they believe a 'woman' should act. Which is fucking misogynistic!
The only way a person can experience life as a woman, is to have a female body, formed around the production of large gametes, even if it doesn't produce those and to navigate their life based on the decisions they and society makes that revolve around them having that body.
A male can conceptualise what it might be like to be a female, but that is all it ever is. They either do it because they don't feel they fit into how they conceptualise how a male person interacts with the world (ie. their own stereotypes around being male) or they do it because they want to be seen as a female (using their own stereotypes of how a female navigates life).
The logic cannot be any different than that I am afraid.
To think the statement your relative made is a valid statement around what a woman is, means that person believes in post modernism and certain philosophical beliefs. And not one person on this planet needs to comply with the demand to affirm those beliefs.