There’s no indication that Elias was NOT sitting in his chair for the majority of mag92 only to stand up and stand in front of his desk once he was alone with Jon. That during the “Elias am I still human?” scene after the “you still bleed” Jon didn’t touch his neck without thinking and didn’t get some drying blood on his hand only to then stare at it. That Elias didn’t, without looking his way, seemingly absent-mindedly gently wrap his hand around Jon’s wrist and pull it down to ground him, while making it appear as if it was an act of feigned kindness that should never be acknowledged.
You cannot disprove it.