That's a very interesting interpretation.
I see you have taken viraj (Vai-raj-yam) - as lack of energy.
But I would like to humbly disagree. I think, in the older upanishads like Brihadaranyaka Up, pArivrAjyam is dealt with differently.
It is connected with Vai-rag-yam ie absence of 'raga' ie Tyagam or Vyuththanam of eshanAs ie Tyagam of Desires. Even a person who is fully capable (endowed with energy) of living in this world, might not feel the desires or eshanAs.
So, in (4.4.22) of the Brih Up the Sruti says, 'to US who enjoy the bliss of the Atman, of what use is children, money or any of these other paltry worldly pleasures? Saying this, those Brahmanas of yore gave up their homes and lived a mendicant life'
It doesn't suggest to me a lack of energy.
It suggests that, from an higher level of self-sufficiency with the Atman, the Brahmanas of yore gave up this lower world for Sannyasa.
In the Gita too, Krishna mentions this idea in the sloka 'Yastvaatmaratireva syaad....'
यस्त्वात्मरतिरेव स्यादात्मतृप्तश्च मानवः . आत्मन्येव च सन्तुष्टस्तस्य कार्यं न विद्यते .. ३.१७..
yastvAtmaratireva syAdAtmatRRiptashca mAnavaH .
Atmanyeva ca santuShTastasya kAryaM na vidyate .. 3.17..
But for that person who rejoices in the Self; is satisfied with the Self and is contented in the Self, no duty exists for him.
Of course, even a person who feels Vairagyam due to other reasons than eshana-tyagam, like the death of a beloved wife for example, might take up Sannyasam, as is seen in real life. However such Sannyasam, while not prohibited, is considered a lower form of the ideal, since the eshanas are still likely nascent in the individual. And he might, at a later stage even give up Sannyasam. This was the case with the father of saint Jnaneswar, who went on Kashi yatra pursuing Sannyasam, however soon returned to take up Garhasthyam once again.
