In my opinion because Ashgabat is a "City (şäher) with the status of a province (welaýat)" (as apm-wa write here : https://wiki.openstreetmap.org/wiki/Turkmenistan#Administrative_Subdivisions) it's relevant to tag it at the same level as a province.

I agree with "The relevant fact is that Ashgabat is "equivalent to" a province" and that why I think it's consistent to rank it has the same level (even if it's not the same administrative structure, it's equivalent). So to put it a an equivalent level make sense for me.
