Yes, Harvard has the right to prohibit an organization from holding an event on its property, and it has the right to suspend any organization that it finds is acting in a way that is antithetical to its mission.
If you want these folks to spout their venom freely and intimidate other students, invite them to YOUR house and let them do it there.
“spout their venom freely”
And who defines venom? It seems you believe Harvard as an institution can. Which means if you don’t use the proper pronouns you are disallowed. Or if you are against abortion you can’t protest with pictures of aborted babies because that’s venom. A lawyer is disbarred because he questioned the 2020 election, more limits on free speech.