A mouse has a pointer that is on the screen even when your not clicking.
Touch is different. If you are not touching the screen there is no touch.x or touch.y, so that means that touching the screen is in effect the same as clicking.
If you want to use touch-input there is no pointer, so your player can't follow it. If there is no touch, touch.x will be 0(zero) and touch.y will also be 0(zero) so your player will move to 0,0 on your layout.
If you want the player to follow your mouse pointer you should use the mouse, not the touch.