Your entire hypothetical dialogue is confusing as well, since your hypothetical person isn't using correct words either. The situation where C + 6 of something = B is with scale degrees (C moved 6 scale degrees up is B). And then you say "I currently mean tones", when 6 "tones" has the exact same grouping problem you are criticizing (because 'whole tone' and 'semitone' have the exact same meaning as 'whole step' and 'half step', only now 'scale tone' is in the group too). This artificially lengthens the example.
"The tritone of this note is 6 steps up" "Gotcha, so the tritone of C is B" "No, that's scale degrees, by 'step' I mean 'half step'." "Oh, so it's F# then." Done.