That's not all he could have done at allHow? What do you think he was going into that situation to do?
I mean when someone’s running towards you with the ball I would imagine your main thought would be to try and tackle him (if he keeps holding onto the ball), to smother, if he kicks it and you’re close enough, and these days especially a distant third would be to bump him.
And I have no reason to think he went into that situation planning on bumping him, but once Day kicked the ball and tackling was off the table, and he wasn’t close enough to smother and that was off the table, and bumping isn’t really allowed in that situation any more, I think he just did about all he could, which was to try and stop, to avoid a big collision, and to turn to protect his chest- which would just be an instinctive move for almost anyone to make, when they see that someone’s about to crash into them at speed.
Get yourself in a position to tackle. If he gets rid of the ball your hands are out to protect yourself. He then could have quite easily just placed both hands on him to slow the impact down.
You stick a shoulder out to a fast moving player there is a chance you are going to get him high and cause damage.
Call it a bump or a check but that's the action he chose to do and it wasn't his only option.