In BrihadAraNyakaM also (IV-4-22) the qualifications for sannyAsa are enunciated: "The one who wants the spiritual world, renounces the present world and his home.
Because that is how in ancient times the learned ones whoi studied the spiritual vidyA just discarded the desire for kith and kin, desire for wealth and property and desire for the other worldly attractions and they left home literally as beggars".
In every work there are always expressions of different opinions but following them there is also the reconciliation passage that comes later. So also in this BrihadAraNyakaM, earlier to this passage in (III-5 ) it says "AtmAnaM viditvA", that is, cognising the Atman, ‘discarding desires for kith and kin, wealth and property and the other world, they run away as beggars’.
Here the words "AtmAnaM viditvA" looks like saying ‘after one has cognised the Atman’. It appears that this means, in contrast to what was said earlier, namely the earning of eligibility for SannyAsa for the sake of earning the Atma-jnAna, it is now said that sannyAsa takes place after the acquisition of jnAna.
This is a legitimate question; but the answer comes if we carefully examine the context.