Nonsense. They can be detained while information is awaited on their legal or illegal status and they can be held for an undetermined period of time.
One of the reasons for a law, any law is to make the commission of a crime in that area unpalatable. The illegals now know they may get stopped for any reason if police deem them to have committed any offense and from there have their status checked which could lead to incarceration for what could be an extended length of time.
Of course, there will still be legal efforts to stop section 2b. Other states will take note and adapt. Here's my article about this issue and my state of Arkansas:
Hope your right. Hope they build some nice spartan tent cities for the millions about to resume their exodus to the promised land.