He's right you know. Don't forget the noncery and loli culture that is going on some of the largest Mastodon instances such as pawoo.net, baraag.net, mstdn.jp.
Totally illegal explicit content in the majority of countries, only found on Mastodon.
Twitter is the only mainstream social network that is absolutely inundated with hardcore pornography. Also, Twitter has no shortage of child sexual abuse material:
On Mastodon, each instance is able to restrict other instances based on their own policies. Unless you specifically choose to join a Mastodon instance that does not restrict pornography, your instance will not synchronize content from the porn-focused instances.
Totally illegal explicit content in the majority of countries, only found on Mastodon.