Why would you as an advertising agency advertise where your clients' ads might show up next to furry porn or Neo Nazi propaganda when you could buy ads cheaper elsewhere amd with people who can assure you that won't happen?

You wanna answer to share holders who might just so happen to also be Jews or just agree with the general consensus that being a Nazi is pretty bad?

Twitter is an advertisement company and if they're placing your ads next to someone calling for the death of all Jews they're a terrible one.

There's a reason why you only see certain companies advertise on 4chan and porn hub.