I think we should all calm down a bit. There are a myriad of ways that your army can be instantly obliterated in a game of Apocalypse. With 80,000 points per side, if the enemy team suddenly decides that they wants your 4000 point army dead, it's dead. Even if we only allowed Codex units, and banned all datasheets and assets, it'd still be 80000 points on 4000. Emperor Titans are just one nice big scapegoat for everyone to be angry at when it's suddenly pointed in their direction.
I think the person I feel most sorry for in all of this is the guy who's actually bringing the Emperor. I don't know him personally, but assembling an Emperor Titan is no small feat and I'm sure he poured many hours of his life into constructing one. Yet he is completely vilified for bringing one to the single game type it's allowed in. It seems like for him, there's two possible outcomes: either his Titan is destroyed/crippled in 1 turn, and he basically gets to do nothing, or it survives and inflicts damage appropriate for a 4000 point model, in which case people whine about the fact that he dared to put it on the table. Seems like the poor guy can't win.
I understand peoples' reservations to be pitted against such a towering monstrosity, but just remember that it's not the only army-busting option available to either side. It's just something that needs to be accounted for when forming a strategy for your side, and there are plenty of resources available for destroying or disabling a single model.
In short, it's not as big a deal as people make it out to be. Everything being on one table means that there's more than adequate resources to deal with pretty much any silly shenanigans from the other side. In many ways it's actually a better case than everyone being split up.
I do hope the people that dropped out reconsider joining, as I think the more people we have, the better the event will be.