That's true in most states, IF the alarm goes off when you try to exit. Of course, if the alarm goes off, they suddenly have a pretty solid basis for thinking that you might be stealing something, and consequently that belief becomes a lot more reasonable on their part. In that case, they gotcha, so you're better off playing along if you really didn't do anything wrong.
But in this case, I think the original posted was concerned about the reasonableness of demands to search and possibly hold someone even when the alarms don't go off - i.e., when they don't have any particular reason to suspect that you've actually stolen something.
It looks like the deck is stacked against the shopper. You're definitely screwed if the exit device goes off and even if it doesn't, the LP guy can make up a reasonable suspicion excuse without even trying hard. Subsection 6 sounds even worse since it talks about what can happen to you if you resist! The only escape clause is the "while committing or after committing theft of property" clause which, I would argue vehemently, renders the penalties of (6) moot if you are not shoplifting. Holy police state, Batman, it is time to shop online!
I guess my strategy will now be to stop at the direction of the LP guy but refuse to leave the exitway and demand that the police be called right then and there. No way would I give them a chance to "make the case" by planting something on me. Parents should be real careful that their child hadn't picked up any merchandise unbeknownst to them.
PS I am not a lawyer not did I sleep at a Holiday Inn last night.