On mobile, using tap to move, I can hold to keep walking. So touch and hold the fridge, it may get you behind or overlapping with Harvey to access. Sometimes it doesn't work though.
Also, it looks like if you stand on the other side, at the foot of the stairs, you can access the fridge from the side. Sometimes I have to zoom all the way in to be able to tap the exact right tile.
Another suggestion is to put a fence and gate around your fridge so he can't do that! Or get a mini fridge and put it where he never stands.