That’s a risky step to take for any group/institution. It’s one thing to fire someone or ban them from your premises or events. It’s another to broadcast that person’s name to the public.
There are risks in naming the individual. One can sometimes mitigate those risks by stating only the most empirical facts: "we have, in the past, entrusted (individual name) with DM duties at (convention name), and as of the current con, we will no longer entrust (name) with DM roles." Astute readers may wonder what story lies behind this decision, and may find out - but hey, the con didn't make any public statements beyond literal and verifiable facts.
There are also risks in NOT naming the individual.
One of the latter risks, is that when word gets around, about "that DM who ran Things from the Flood", and there are two DMs who ran Things from the Flood games at UK Expo 2019: the omission of Rolfe's name, increases the risk that people will mistakenly blame the *other* TftF DM for Rolfe's actions.
Another of the risks, with Missing Stairs, is that he'll go elsewhere and do the same thing, getting booted from venue after venue, while at each of those venues he racks up a higher and higher total count of players with shocked faces. I doubt that this particular DM has as many options in the UK, as he would in the USA; but suppressing names has had a someone-else's-problem effect, in other domains, which I will not deign to enumerate here.
Sometimes people accept risk *to themselves*, in order to avert or reduce risks *to others*. IMO this is the core of heroism. I cannot tell UK Expo what risks it must take, for the greater good; that's their choice, not mine. But if my local game con refused to take risks, and *in the process left others at risk*, then I'd be less interested in going to that con to fulfill my TRPG heroic fantasies.