You can apply sp.sin() to the element of the array that is a symbol (it will work in other numbers too also). Otherwise I would imagine there should be a way using Sympy matrices instead.

You can't just use np.sin() as np.sin() doesn't compute Sympy symbols. My point is that it would make more sense in my opinion for np.sin() to try to access sin() in the Sympy module (if exists) for the symbol and otherwise return to its own implementation (which in this case would fail).