It's not ideal, but it's reality. (I'm looking at this from the perspective of the university; which is getting heat)
You have one side willing to commit crimes and the other who wants protection. The University needs the money to separate the two. The ultimate solution would be for law enforcement t to break up the criminal organization threatening citizens, but california can't provide police protection because the criminals are their base. So we have to wait for the federal government to do it.... and military intervention isn't acceptable... yet.
So what's a reasonable compromise in the meantime? Shapiro can cover costs for security because he's a paid speaker. It would be no different than Ariana Grande holding a concert in Afganistan. Some locations cost more than others.
When I said "free speech isn't free", I didn't just mean $$$. We have that right because we're protected by a military force keeping others from taking it from us. In this instance, the threat is from our own citizens, so it's a little complicated. The price of providing that freedom is targeting our own (misguided) people. We paid that price before to force desegregation... are we at that point again?