The purpose of using a non-newtonian fluid in personal protection is that it is flexible. It can conform to an arbitrary shape. You can flex and move until the shear rate exceeds a threshold. Then it acts like a rigid solid
For a phone, it’s silly. Phones are, so far, rigid and have a fixed shape. There’s no advantage to using non-newtonian fluid. Unless you just like having a squishy case. Otherwise, plain ol’ plastic cases work the same.
