What it would prove is that it is quite possible for 91 year old priests to give Communion on the tongue to hundreds of parishiones daily without touching anyone’s tongue.
Give that, it would follow that if a younger priest is having difficulty, the problem is at his end, not with the method. Just like I am sure there are EMHC’s out there that don’t wipe the right spot on the chalice after each use.
Since you seem to be aware of priests that can’t help but stick their fingers on other peoples tongues during this process feel free to have them contact Fr. Valerian. I’ll PM you the parish’s contact information.
He’ll set them straight