Well, a connection between exit router and ISP using "100 base T with 500m UTP-3 cables and 10 dumb hubs" is out of the specification of IEEE standard. The user won't expect M6 solution would work on an out-of-spec connection nor should this WG. But the same user would expect M6 solution maintains reasonable performance (or degrade gracefully) with his "within-spec" wireless link to ISP independent of the weather condition.
With some definition of "within-spec", what performance is expected by the standard?