I would agree with that. The police are given quite a bit of latitude in such situations. If the police receive a complaint, they will more than likely investigate it.
I do not know why the Texas law is written in an ambiguous manner, but it was probably so toplessness could be permitted without raising the ire of the conservatives and the "Religious Right" movement in Texas, or some deal was cut for something in return.
I would look for the extremists to try to overturn it at some point in the future, "Because we just can't have women exposing themselves for goodness sake!"