HELP,

hired a contractor to remove old popcorn ceiling (tested no asbestos)

for some reason, the ceiling has drywall then a layer of plaster then a
layer of compound then the popcorn ceiling. The contractor is now
telling us that it's too difficult to remove the popcorn ceiling and
that if removed the plaster would be damaged to a point that it would
be difficult to make a flat smooth surface. Instead he has just put
compound over the plaster.

Question:
1. putting joint compound/plaster over popcorn ceiling kosher?
2. what's the longevity of this process, prob bad if ceiling gets wet.
3. will removing popcorn placed over plaster really that bad to remove
or is contractor full of it?
4. he already covered about 1/4 of ceiling, any recommendations on what
we should do?

Thanks

T