The core goals of no-platforming have to be defined. If the core idea is to prevent harm to marginalised identities, surely the best way to do that would be to publicly engage with and refute ideas which threaten them. Stifling them through censorship seems counterintuitive.
The purpose of no-platforming is unclear. Surely if the purpose is to make sure that harmful ideas don't spread further, it is important to engage and debate them. The first issue with no-platforming is that you take away the opportunity to interrogate and debate these ideas. In doing so, you make it more likely that they will go unchallenged. After all, debating ideas like racism or homophobia are what made people change their minds about these issues in the first place. Unless you show why bigots are wrong, people will continue to believe in the bigoted ideas. The second related reason is that pushing ideas out of mainstream discourse and out of universities doesn't mean they disappear. If anything, they take on a more alluring quality. Nothing help's neo-Nazis more than martyring them by banning their ideas from public forum. Tacitus, the Roman Senator and historian summed it up two millennia ago when he said that the persecution of an idea "fosters its influence". Those that bar ideas "procure infamy for themselves and glory for their victims".  When it comes to speech we find most despicable, it is even more important to debate and challenge, rather than censor it.
Debating ideas isn’t always a surefire way of defeating them. There are many ideas and people who are unwilling to engage in debates on the same terms as everyone else. Oftentimes, rather than changing people’s minds you merely put problematic and dangerous figures on a pedestal and give them legitimacy they wouldn't otherwise have. History has shown that when far-right and dangerous speakers are denied a platform, they lose their legitimacy and respect among the public. Richard Spencer, the prominent American white supremacist, recently acknowledged that no-platforming left him and his followers demoralised and defeated. Exposing students to dangerous ideas isn't the only way to challenge them. Students and the public can also challenge resist them without giving them the legitimacy of a university platform.
P1. The purpose of no-platforming is to protect marginalised identities P2. Protecting marginalised identities is best done by preventing the spread of harmful ideology P3. Preventing the spread of harmful ideology is only possible by debating them C1. No-platforming does not achieve its goals
Rejecting P2: Giving a platform to dangerous ideas for debate is not the best way to protect marginalised communities. Rejecting P3. Sometimes debating simply doesn’t work.