The state of Qatar will not implement a dress because it is almost impossible to enforce, goes against the notion that Qatar is a multi-cultural and tolerant society, and it will play out very badly in the world media at a time the government is seeking to raise Qatar's profile. The article I cited in the OP was discussing the negative implications for the World Cup.

Having said that, there is nothing wrong with a private campaign that kindly requests visitors to behave within the cultural norms of the society (eg be good guests). In exchange Qataris should be expected to be good hosts.