That's the argument leftists use when they keep conservatives from speaking on campuses. I get that here is a gray area in this argument but the answer, IMO. is more speech not less. And yeah, it's fine to boo, shout her down, turn your back on her during the speech or simply walk out.
And speech, which can "incite" harmful, violent physical reactions is NOT deemed "free speech".
We have seen, especially on college campuses, how these anti-Semitic/anti-Israel protests have indeed incited VIOLENT actions.
Regular people have hit the point now, what with the protestors stopping traffic on bridges and highways, invading companies, and now even subways in NYC, where it is possible that should that girl give an incendiary speech at graduation, someone just might over react, as a graduation in America is NO PLACE for such protestations.
Also, that university would be liable, for allowing her to say an anti-America, anti-Semitic, Anti-Jewish trope, IF a person/s decided to sue them for allowing that to be said.
This is NOT a "leftist argument"; sadly, it is what it is in today's society.
And you're just concerned about YOU being shutdown for saying "LETS GO BRANDEN" , or worse, by some lefty or group, in public or in a written message, which is quite different from this situation with a captive audience, there to enjoy/celebrate a happy institutional occasion.