[QuidQuoPro]

Firstly its union with Brahma, not Brahman


Brahma is considered to have all the four immeasurables, which are also existent in those who have put and end to craving


From what I can tell the Buddha is saying that the only real union with Brahma is the end of craving which brings all the four immeasurables to true prefection, which are considered to be what Brahma has


In essence, in this Sutta, he was simply renamed Nibbana as "union with Brahma" (since thats the language that the Brahmin is used to) yet the final outcome is simply nibbana


I wouldnt worry about the Theists though, they have a way of putting their own particular God into the Suttas, Vedantists in particular