That statement would seem to apply once the battery is warmed up, but you'll still have the need for high draw to warm up the mass of the battery when it has had a chance to cold soak combined with taking short trips. Yes, the heat pump still has potential benefit of doing that more efficiently, but still have the same thermal mass of the battery that must be warmed, which requires a set amount of energy. Similar to to energy draw of the AC when the car has sat in the sun, interior is heat soaked, and the AC is running max to initially cool the cabin versus the draw after the cabin has cooled off and AC is just needing to maintain temp.
If your operating profile is shorter trips, then you'll still likely to see show big range losses even with a heat pump. If you're talking about a day long drive cross country in cold ambient conditions, then this would be the case where the heat pump has the most potential for improving range.