Some thoughts on the above conversation:

The discussion is about experiences of the mind - experiences that require consciousness. In this context, I would expand the meaning of consciousness to include the experiences of dreams and dreamlike states, in which we are aware of phenomena that are not exclusively related to immediate sensory input.

We all experience consciousness. We don't deny that there is such a phenomenon. Yet no one knows what consciousness is. The brain is a biological device from which consciousness appears to emerge. Since we don't know the nature consciousness, we should be cautious about making assumptions or claims that suggest that we do.

There is room for speculation as a basis for scientific enquiry. The brain may not be the only environment from which consciousness can emerge. There may a 'large scale' consciousness that exists beyond the confines of the localised biological apparatus. As yet there is no proof, and it is wrong to make claims without evidence - but, as Carl Sagan said, absence of evidence does not mean evidence of absence.

We may reserve judgement, pending the results of research; but experiential evidence makes a significant, and often over-riding, contribution to the understanding of the experiencer. Scientists are sometimes inclined toward dogmatic denial, when in fact they should be prepared to say "there may be truth in that - let's try to find out".
"Time is what prevents everything from happening at once" - John Wheeler