It isn't unrelated. It's "not normal" which was your criteria for restricting gay people from the same. It's also not normal to do deep sea diving, or myriad other things. We should restrict people who do that from marrying as well. Because "normal" is the standard by which we judge.... Less people run in marathons than there ever were gay people. That practice isn't "normal" we better stop those people from getting married too....Totally unrelated. Skydivers, however, should pay higher insurance premiums to pay for their risky lifestyle. Just like gays should pay for the consequences of their lifestyle choice.
As I said, this is the weakest leg of your tottering table of an argument.