I don't quite get any neoplatonism from this. There is a very homo-erotic overtone, but not quite a personal swing off the teachings nor even aspect of any Platonic philosophy, aside, maybe from the notion of brotherly love and its adaptation in the modern eye under 'bromance'.
I get the quip on the conceit; the metaphor is incredibly complex and deftly applied in how it threads through the entirety of the poem as would have been expected from the pre-romantics, and I must say that I enjoy the fact that classicism is a convolute sworn into ignorance by the cloak and dagger thrown off as homosexuality is heralded. Progressive and refreshing, no? I would say yes, had it not been for the scores of Sonnets by both Spenser and Shakespeare that achieve and attempt the same -- but neither of them was truly gutsy enough to be so crude and/or blatant. As far as this conceit can stretch, it stretches beyond the metaphysical and hyperbolic fancy that most other sonneteers would make light of, or believe were just
As a sonneteer, I personally prefer to take cliche and over-arch it into the elucidation of the second quatrain, then denounce at the volta. The juxtaposition of reciprocal justification only offers more depth and doesn't really play, but actually becomes accepting of the conceit. I suppose we could review it as, either you experiment by the flaw of hyperbolic emotive language, or ingratiate it. Neither really comes forth to present the true core of a sonnet, but the former serves the intellect. In serving intellect, whether by humour or engagement, emotion can be handled within whatever binds the poet chooses. That's the beauty of the sonnet conceit - the influence of Plato in most cases simply something to give an illusion of the required humanism (or conviction of thought)... that said, it is not uncommon for any layer of human thought that relates to our direct social environment or emotive condition to bear elements of Platonic theory and philosophy. It is, after all, the basis of what makes us human and what most philosophers have always questioned. The sonnet is a perfect vessel for such introspective processes.
ETA: for those wanting to discuss but unsure of certain terminology.
Neoplatonism is a modern word used to describe personal philosophies that resemble elements of Plato's teachings or that take an educated personal direction derived from them; not every neoplatonic ideal requires the thinker to have studied Plato.
A conceit in literary terms is an extended or elaborate metaphor that encompasses in its concept the entirety of a passage or body of poetry. There are 2 kinds: the metaphysical conceit (exaggerated beyond comparison of the subject in question) and the Petrarchan conceit (the comparative nature is filtered through subtext relating to certain aspects of human emotion through specific references); prior to the Romantics' revival of the Miltonic Petrarchan sonnet revision, the conceit was a common and in many cases ritual and essential element of the sonnet.