Should he be legally allowed to force everyone to 'believe' he is? (Obtaining a certificate asserting that as fact, would entitle him to benefit from the revenue stream from playing the music of Elvis, so it would be worth his efforts)
There's an entertainment industry, and a private amusement, in dressing up.
Some impersonate Elvis. Others impersonate Women. Nobody can actually "transition" to become Elvis. Nor can anyone with a Y chromosome "transition" to become female. Giving any of them an " Elvis recognition certificate", or a "sex change certificate" or a falsified birth certificate, won't make an untruth true.
Women and children are at serious risk from fake 'women'. The Presley estate would not allow any risk from fantasists, fetishists or fraudsters who take their private hobbies or their stage impersonation acts to the point of actually attempting to deceive.
Could I suggest we disallow and discontinue colluding with the language of the female impersonation industry, which has now become a dangerous cult? There Is No Such Thing As Transitioning.
There's No Such Thing As Changing Sex. There Is No Such Thing As Legally Definable 'Gender'. The word has no place in a Statute or a Policy or Practice.