Is Dhamma-thinking considered wise attention?
Yes, if that Dhamma-Thinking is arising continuously without five strings, without five hindrances, and with understanding the real reality, more than trillion times in a second, with it's real relation.
However, most people are thinking of Dhamma with five hindrances in between because they have not enough concentration meditation power, so their mind can't meditate to the end, Nibbāna.