I had this exact injury when many years ago playing goal. I don't think it was his hand at all.
When the shot hit an exposed piece of my upper arm I lost all feeling in my arm and immediately dropped my stick. Then pins and needles started shooting down through it.
He'll have one hell of a bruise but I think if he stays off ice with ice packs on it till Saturday morning - he'll be good to go. Not 100%, but good to go.
(by one hell of a bruise, I got hit on the frontal part of the shoulder and the bruise went down into my forearm, up over my shoulder and onto my shoulder blade, onto my right chest area and met the base of my neck on that side. Excruciating pain is putting it lightly lol)
I know injuries can become more serious the next day, but if that was Hank playing hurt, I am not worried. This dude is a warrior and wants to win, he won't let his finger hold him back now.
Give him the Pens game off, which is likely, and let him decide what he wants to do for final game. I would not be worried if he asked for 2nd game off, and was out of game action for 8 days.
Edit: Sorry, didn't read whole thread, I see its his arm not his finger/hand. I don't read to much doubt in his tweet, he is sore and will get the days off he deserves. Give him both games off and lets get ready to roll in playoffs.