Actually it's not and I'll elaborate.
Regarding the free speech part specifically I'll again ask that we read and pay attention to the contents of the comic made by XKCD and I'll link it again here:
The first panel says in plain text that "the right to free speech means the gov't cant arrest you for what you say". The deplatforming of people promoting harmful views is in no way violating their free speech. No ones being thrown in jail, platforms (and by extension people) are simply making the decision that they no longer wish to host these people and their content. Plain and simple.
Also deplatforming people with harmful views is necessary albeit hard to understand especially if your not someone who is harmed by such views and it's the absolute truth. It's no mystery that people who are not of marginalize backgrounds will never relate to nor understand their struggle but what can be done by those outside those labels, those identities and those backgrounds is to listen and empathize. and that very last bit is a big one that many seem to fail to do constantly.
I'll give some examples. You mentioned the "water turning the frogs gay" statement made by Alex Jones a well known conspiracy theorist and holder of many harmful views. Views which put actual lives in danger even if not directly. A better example I can elaborate on is author J.K. Rowling (which I apologize to any trans folks passing through for even invoking the name) who is a known terf and overall transphobe likely among other things. Her harmful views have put trans lives in danger especially in the UK where she's considered a highly respected and influential individual. The cost this has had is making it incredibly hard for trans folk to have access healthcare among other things I'm sure. The info is online and can be researched but of course be discerning in what you read.
The point is when you continue to host people with certain view it's not only perpetuating the spread of what they say but also invites other with those same views, normalizes it and perpetuates it across whichever platform. When you deplatfrom a person who is racist that's necessary to protect people who are victims of racism. When you deplatform people who think school shooting are a hoax your protecting the victims of said events. When you deplatform people who are deniers of genocide you not only protect victims of genocide but also prevent such a thing from happening again. The point is that deplatforming is necessary because the longer those views are allowed to exist and persist and permeate spaces the more people are put in danger even if indirectly. That's why Donald Trump had his social media accounts terminated because his words eventually led to violence being incited (and there is undeniable evidence of that so I will not debate it).
Sometimes violence doesn't just outright happen. Often times it's a slow build. It starts with micro-aggressions, small actions, maybe a little abuse or assault here and there but then as it build over time then you get the big explosion (as we witnessed with the build up to the Jan 6th insurrection at the capitol). I'd imagine that even in other countries outside the US the same happens (I'm merely focusing on the US as that's where I am). Deplatforming people is not silencing them, no one said they can never ever come back but if it's made clear that their views are harmful or potentially harmful and people see that having such views bears consequences then it serves as a lesson and a warning.
This is why the notion of so called "cancel culture" can be so harmful because rather than acknowledge and address genuine evils or at the least harmful veiws or ideas it instead directs concern to how "you can't say anything on the internet because ppl will cancel you for it later" when that's no it at all. Actions have consequences. What you say can have an affect/effect on the lives of others whether you bear witness to it or not and the more you dismiss those things the further you endanger said individuals.
Like I just want to say that if I seem like I'm angry as I'm speaking on this it's because in part I really am but I'm also tired. I've seen people here and in other places be so dismissive to the suffering of others and struggle to understand how people can lack basic empathy but I guess that just goes to show where things are on the planet as a whole. It's easier to dismiss the actions of others and scold the ones who raise their voices about it rather than bothering to give even a single iota about the well-being of others. No ones saying you can't say things. No ones saying you can't follow or interact with certain folks. If anything all that's being asked is you at least try to pay a smidgen of attention to who those people are and where they stand and if their views could be hurting or harming your peers. if anything I'd say don't be surprised or angry if people choose not to interact with you (I certainly wouldn't) because of whatever views you have.
I keep writing these longs posts but if anything it just feels like I'm screaming at a brick wall and all my words are fallen on deaf ears but all I ask, all I hope, is that some of you (any of you) can learn or try to have at least a tiny atom's worth of empathy because some of these replies are incredibly disheartening.