That's the best they can do now.
Seriously, given the situation, they have to move on and make everyone forget. Explaining things would be useless. You can't make a hater think rationally. And if they wait too long, they risk just being forgotten.
Delaying again won't help the things die down. They have already delayed too much, but I guess the girls' spirits aren't very high right now.
Seriously, there is nothing they can do, except what they do best: singing. So just do that, and everything should work out, somehow. Yeah, they might be criticized again and it might kill the rankings for Mirage. But, hey, they will criticized whatever they do, at the moment.