We can't say for sure
Yes we can.
we should take the experimental [sic] quality of matter for granted
No of course we shouldn't be so obtuse.
at least it shows that it's not necessarily safe to assume the non-experiential quality of matter outside the consciousness of humans and other species
Yes we can safely assume this cup I am holding experiences absolutely nothing. You are dishonestly passing on the burden of proof.
That which can be asserted without evidence can be dismissed without evidence.