It’s not about rank or age. It’s about who’s been present at the last battle of the War of the Last Alliance. Also, at the time of the depicted scene Elrond never was in Valinor, so at this point in time Gandalf definitely easier Elrond’s senior by orders of magnitude.
This does raise the question “Does your age count when you’re in Valinor?”
Because it’s literally the undying lands. Are we really going to pull rank between two functionally ageless beings? Seems petty.
It’s not about rank or age. It’s about who’s been present at the last battle of the War of the Last Alliance. Also, at the time of the depicted scene Elrond never was in Valinor, so at this point in time Gandalf definitely easier Elrond’s senior by orders of magnitude.