yes, for TWR as a dzogchen practicioner, „This is a dream“ (instead of „Is this a dream?“) is the statement that cuts directly to the nature of reality of both day and nighttime experiences from a rigpa vantage point.
From a conventional vantage point, this statement/view of reality which does not differentiate between daytime and nighttime experiences does not seem to make sense (from a conventional dillusional point of view).
Having switched back and forth between both statements during daytime practice, I find that it stretches the mind in a yogic way, i.e. loosening slowly mind reifications, analogously to slowly loosening a tight body by practicing yoga).
But, since this view of reality is so directly connected to dzogchen practice, it should be explained and introduced by a qualified teacher to an interested beginner. Otherwise it is said that there will be intellectual misconceptions to the view and improper practice.
From a conventional point of view, the statement „This is a dream.“ does seem pretty psychotic. 
We had some great discussions on the subject already and I love B.Alan Wallace‘s explanation by using the analogy of the Dona Sutra: