Can deck posts be rested on a patio slab?
Generally speaking, floating slabs are not suitable as post footings. You're likely to see cracking under load, and if the soil underneath is unstable you'll see substantial settling.
If the question is whether it'll work in combination with your other post footings, we can only guess. It depends on the exact nature of the soil substrate, the amount and frequency of rain in your area, the total load on the posts, etc. None of us will be able to give you a better answer than what was stated in the answers to your other question.