Absolutely nothing short of everything! Which is why they should go all out, anyway.

Himeka will definitely want to try and talk with the Acolytes first when they find them since it would probably be better if they had some to answer with WTF all this was about...but you never know how that will go, so knocking a few heads may be necessary.

That being said I'm sure that the island itself or how they get to the Lost down there won't be very safe either, so there will probably be reason to fight either way.