First off all this Legaleagle guy is a girl. I do not represent this site, I am merely a user of it like you.
Second, I answered your question initially. You did not agree with my opinion and stated that "you did not buy it." In my jurisdiction, yes, a store has the right to stop you if the sensors go off. That is what the sensors are for. If you think that is invasive, having security trail each and every person in the store would be a heck of a lot more invasive.
Furthermore, if you resist or take off after the sensor goes off, the police will likely be called, raising your chance of being arrested. Again, if you do not like how a store is treating you, don't shop there.
If you want to shop there, or have to shop there, than you are going to have to resign yourself to the hassle of being stopped if the sensors go off.

