There are aspects of the law that are good-- strengthening the reporting requirements, etc. to make sure an abuse case can't be suppressed by the school administration, et. al. The problem is quite profound in terms of our current legal system in fact. A comparable case is that "it is legal in the United States to buy certain types of high explosives, but not to make them", as the buying can be regulated so that not just anyone can go out and buy TNT at the local "five and dime let's make a bomb shop". But because of the Bill of Rights, nearly anyone (felons excluded) can own just about any type of "arms" (weapons) because we have the right to keep and bear arms. And that right is strongly protected.
Even though we all agree that teachers coercing or molesting students is a bad thing, it's not a preventable by destroying an aspect of the bill of rights thing. They call it the slippery slope and it's the same kind of thing with free speech. You are free to yell "fire" at the top of your lungs --but not in a public place --unless there is actually a fire. So the laws designed to protect students can't just say who can talk to whom and how as a method of preventing child abuse, they have to be crafted so dang specifically that they fit existing crime statutes, for example, it's illegal to engage in speech "soliciting" or "coercing" behaviors such as sex with minors, prostitution, etc., but not to call and talk to a student about an activity or grade. And a parent monitoring a child's FB account would have the right to raise holy hell for any teacher risking that kind of speech, etc. online anyway.
So the likelihood of the freedom of speech issue surviving a court challenge as written is probably nil.
(EFF ==> Electronic Freedom Foundation, btw).