There is no First Amendment right to shout down a speaker. If a governmental actor, such a public university, sides with the heckler by canceling the event or refusing to protect the speaker against use of force, it has failed to uphold the speaker’s free speech rights.
In Forsyth County v. Nationalist Movement (1992), the Supreme Court held that the First Amendment protects “[t]hose wishing to express views unpopular with bottle throwers . . . Speech cannot be financially burdened, any more than it can be punished or banned, simply because it might offend a hostile mob.”
source: https://www.thefire.org/best-of-newsdesk-rejecting-the-hecklers-veto/
Thanks, tbw2. Good points.