Why not remove Chrome, Safari and E-mail clients for inappropriate content too? Why not WhatsApp, Skype or iMessage? Telegram is just a wire, it's up to the users if they want to use it to talk to other users that speak 'inappropriate'.
This is why I will never buy an iPhone (though I don't mind a MacBook as long as root access and legal ways to install Linux have not been locked on them yet) - I want to use the device the way I want, have full control over its filesystem, run the apps I want without all that store bullshit (which hits even harder if you live outside the USA by the way, in synergy with your local government bullshit and with what corporations think about your region market) and decide what is appropriate for me myself.
Today Apple is a fascist organization. Historical fascists did fairly good in eye-candy design and hardware quality too but that's the only good part of them and it's pretty much ruined by so much crazy fascist bullshit to tolerate in exchange.