From the angle of vision of time, the creation and dissolution of the material world, the expansion of Garbhodaksayi Visnu, Karanadaksayi Visnu and Ksirodaksayi Visnu, (the lila of creation); the spiritual body is something to attain.
From the angle of vision of eternal Vaikuntha and Goloka, "The spiritual body is already there, but we are now covered by this material body."[Srila Prabhupada]
These two apparently opposite concepts are both simultaneously, inconceivably, one and different, acintya bheda[a] bheda tattva.
Yet to think that the eternal servants of Krsna fall or dream that they fall from their eternal service is an aparadha not bhakti or devotion. Therefore the siddhanta must properly adjust the different angles of vision to come to the devotional conclusion. It's only common sense, otherwise the words: nitya baddha, saddha siddha etc. would not exist.

Well written and point understood, I agree with you here

another point that I think is important to understand is that Srila Prabhupada was speaking directly to disciples who had been initiated with the bhakti-lata bija.
so, for them, yes the seed of the spiritual body is already there.

But, I don't think you can apply what Srila Prabhupada said or wrote to his initiated disciples to every Tom, Dick and Hairy jiva in the material world.

Sure, for devotees who have been initiated, the spiritual body has already been acquired in a seed form in terms of the particular brand of bhakti they have imbibed from the Guru, Mahaprabhu and the Rupanuga sampradaya.

So, for Prabhupada to tell a disciple "your spiritual body is already there" is not very impracticle because in fact the spiritual body is acquired in seed form at the time of diksha.

The seed of the spiritual body must be fully realized in course of perfection of devotional service beyond the modes of material nature.

The followers of Srila Bhaktisiddhanta Saraswati Thakur consider him to be a nitya siddha bhakta. IOW that he and Srila Bhaktivinoda Thakur came down from Goloka to serve Sri Chaitanya Mahaprabhu by expanding His divine mission (sankirtan). The followers of Srila A.C. Bhaktivedanta Swami believe the same about him. If we think that we are nitya siddha, also, then we have no way in which to distinguish ourselves from them. It that sense, 'it all becomes one' which is similiar to the siddhantic mistakes made by the followers of Sankaracarya. Again why is the term 'nitya baddha' appear so many times in the Caitanya Caritamrta? The answer must be that it was used by Sri Caitanya Mahaprabhu, Himself. From the eternal viewpoint, everyone is nitya siddha, but we will not apply that viewpoint when thinking about our gurus who include the eternal associates of Krsna (parivars) because our logical conclusion would be anti-devotional.
PS: And I also agree with Sonic Yogi in the last post #223.