But yet, there are many Dominican monasteries in operation today, even in the U.S...
While I understand that non-Catholics don't see much difference between one Catholic in a religious habit and another, a Catholic friar - which this man claims to once have been - would be well aware of the distinction.
While it is true that monasteries have often been repurposed for use by friars, no Dominican - no matter what building he lived in - would refer to himself as a monk.
Did this get cleared up? The establishment in DC is not a monastery. It's the "Dominican House of Studies" for the Province of St. Joseph, The Eastern Province. Most of the other places are "priories." The monasteries are where the Second Order Dominican nuns hang out. They are an enclosed contemplative order.
Dominic purposefully did not want monks. He wanted "canons" and used as a basis the rule of the Augustinian Canons. The Dominican 'rule' is not a monk's rule, and the Dominican life is not a monk's life. The Dominican/Franciscan 'revolution' was set against the established and stable monastic orders.