Ok, but it is more accurate to say that the converse, i.e. that the wavefunction does "really" collapse, is not accepted either.But you should never provide the misinformation that (i) this is an accepted idea in standard physics and, more importantly, (ii) you have experimental evidence to back it up.
In my original post, I did write that:
Apart form the last sentence, this is what the quoted article says.Then the state of the box is not a classical state but we cannot do any experment in practice to demonstrate the non classical features of the superposition. That inability cannot be used to argue that the state is classical.