Of course they are "allowed to", which is kind of a ridiculous notion in war in the first place.
But they're in a complex enclosed by land that will soon be under full control of Israeli forces.
All info getting out will go through Israeli channels.
Independent observers won't be let anywhere close.
And when the peacekeepers end up disappearing, the west will strongly urge Israel to conduct an investigation into the matter.
While delivering another shipload of weapons and a cheque over $10B.