We recently enacted a similar law that is still being tested. That one came about as a result of the UCSB shootings a few years back. I don't feel all that comfortable with the legislation, legally, as it smacks of subjectivity without due process ... but, I have not personally had to deal with it so I cannot say with certainty how it might be applied. Conceptually, it appears ripe for abuse ... though, I suppose the same can be said about most any legal process.
The preventative process, and the use of tools for protection, are why I am a HUGE advocate for restraining orders. Without them, the police can often do nothing to intercede when the behavior is, objectively, non-criminal but still menacing when placed into context.