Y not said: “But how is it that the Buddha is giving instruction on how ‘attain’ the realm of Brahma? Which is also a trap in the sansaric journey?”
That is correct. The Buddha NEVER advocated striving to be born ANYWHERE in the 31 realms. That is because one could not ELIMINATE future suffering that way, even if one could get temporary jhanic bliss. Even a billion years in a brahma loka is still a brief time compared to the sansaric time scale!
This is a long story that I did not want to get into yet. But I will try to give a brief summary in a few days. I am on travel for a few days.