Is the statement "Claims demand evidence" always true?

[Mudhammam]

Qualia cannot be shown to exist in any physical system without a question-begging redefinition of the word into physical terms.

Do you mean, if I say, "Hey Benny, what color is my shirt?" and you say, "red," what I perceive as "red" may in fact be perceived by you as "green," and thus, I have no way of knowing if my perception of "red" (or any other phenomenal experience) is strictly had within or without the context of a physical system? Cannot this be similarly framed to posit the existence of Cartesian Egos or other "nonphysical" entities, though, at least in this instance, our experiences are directly perceived -- if not communicable but only in terms that may or may not accurately represent/convey another's experience?