I guess there is no problems from a legal perspective if tour pilots have the 7th day off,however from an economical perspective it isn't profitable to have usable pilots off duty.
Maybe some operators have mis-interporated the rule ? This very subject was bought up at a recent CAA audit with the company I work for. I also was under the same impression as you KL about the 7th day off,however after consultation with the CAA blokes it become evident from the rule that 7th days are “NOT” required to be free of all duty.
Dwyer may have been weird sometimes,however he wasn't stupid,he knew the meaning of this rule !