‘Existence’ is a term that tries to consolidate the activity of appearing into a noun. The activity of ‘happening’, ‘appearing’ never ends up as a genuine noun. The term ‘existence’ is, so to speak, a fake term. Form is, as an appearing phenomenon, in that category if it claims to be real via a mental activity of believing that it is real.
The inherent substance in appearing and disappearing forms is emptiness. (The term ’emptiness’ implies that phenomena do not have an independent substance.) The only substance there is is unboundedness. Some call it ‘freedom’, Jim Newman may call it ’empty space’, Tony Parsons may call it ‘unbounded energy’. They don’t want to call it ‘awareness’ but they say ‘it is obvious’.
That sense of obviousness is only possible when the facts a ‘lit up,’ enlightened. ‘Enlightened or Enlightening awareness’ are terms they reject because there is no one to own such an awareness. Nevertheless, unboundedness is ‘obvious’ (quoting). That claim (that unboundedness is obvious) can only arise within the universal light of clarity – that could be called enlightened awareness.
These terms do not point to something special. They point to the obviousness of timeless ordinariness. These terms are only misconstrued by concepts that arise from a time-bound view. To prevent such misinterpretation, Tony et al. avoid them. At least, that is my explanation of why they avoid these traditional terms like poison.