Lockdown just seems to mean chaperoned, and even the dumbest of celebs will be able to count, and realise there aren't many people in compared to previous editions.

I think they should let them get into the house for a couple of days before reveals start happening. Too many opening night twists have made it obvious that something will happen. They'll all know who else is going in, so when they don't show up, they'll work it out.