Everett K. Rowson is one of the most eminent scholars on male-male sexuality and eroticism in classic Arab culture. His "The Categorization of Gender and Sexual Irregularity in Medieval Arabic Vice Lists," in Julia Epstein and Kristina Straub, eds., Body Guards: The Cultural Politics of Gender Ambiguity (New York: Routlegde, 1991), pp. 50-79. and "The Effeminates of Early Medina," in Journal of the American Oriental Society 111 (1991), pp. 671-93. are milestones in the history of Middle-Eastern Gender Studies. But there is one point on which he is fundamentaly wrong: the meaning of the Arabic term ʿiḏār.

Convention stated that a boy lost his allure once he became adult, the transition being marked by the growth of his beard. The first down on the cheeks was universally considered an enhancement of the boy's beauty, but also heralded its imminent termination. This crucial transition became an extremely popular topos for poetry and soon enough generated a response defending the unspoilt beauty of a fully bearded young man. Both points of view continued to find advocates for centuries, resulting eventually in anthologies of "beard poetry" devoted exclusively to this debate.
Gay and Lesbian Literary Heritage (ed. Claude J. Summers), New York: Holt, 1997. p. 449
now on the web.

It is not the case that "[t]he first down on the cheeks was universally considered an enhancement of the boy's beauty." It was generally considered to be the end of beauty and a signal to end the pederastic relationship.
There are no anthologies of "beard poetry." The "extremely popular topos" was the first sprouting of down, not the beard. Nobody denied that even the first signs of facial hair were a blemish, but as you might prefer a piece of furniture with a scratch, or a stained jacket you are accustomed to to a new faultless one, you may prefer not yet to dump the 15-year old; but to sing the beauties of fully beared young men is scandalous (I do not say that desiring a 17year-old did not exist in reality, "only" that Arab (Persian, Turkish, Urdu) poems are strictly pederastic).
The word used in these poems is never laḥiya (beard) [or ḏaqan/ḏiqan (chin, beard)] but ʿiḏār, pl. ʿuḏur (down, fluff, peachy fuzz) [or ʿāriḍ (cheek, downy cheek)]. They speak not of a forest of hair, of thick standing hair, but of the first sprouting as of ants on ivory, of writing on parchment, of a gently flowing rivulet – highlightening chubby cheeks, not hiding them as a beard would. Some defend their going on fucking the boy (who can not blackmail them anymore, because nobody else would take him now, that the prime of beauty has passed): the boys are tamer knowing that their value has declined.
In Persian poems the nawkhatt, the first trace of a moustache was often welcomed, but the first growth on the cheeks was the no-no.
Outside the "down poetry" there is occasional reference to sex with a fully bearded man, even with a grey-beared, but I never came across a poem speaking of "the unspoilt beauty of a fully bearded young man." I am curious what anthologies of "beard poetry" Rowson had in mind.

Furthermore, it is not correct that "the sexual submission of one adult male to another was assumed to be [always] the result of a pathological desire to be penetrated," as Rowson claims. It could as well be the result of greed or of physical weakness (normally paired with feminine beauty or social weakness = poverty, no strong brother, no father with standing in the community).

Let me recapitulate:
a) In the post-classical anthologies one finds lots of ʿiḏār poems – the normal word for beard being laḥiya.
b) But more importantly, the images in these poems show that a full beard is NOT meant.
c) These poems are apologies: even when someone states that the ʿiḏār is an embellishment, with the whole corpus in mind, it is clear, that it's understood that facial hair objectively is ugly, but that the boy in question has other qualities that make up for it: on himeven hair becomes esthetic.
d) If Rowson were right, if these poems (or a good part of them) were about the beauty of fully bearded young men, sometimes the poetical I should fall in love with a young man.—In reality they always fall in love with a boy, but defend there prolonging the affair a bit.
e) The few poems about fully bearded men are mostly not about fully bearded young men and their beauty, but ridicule a fully bearded old(er) man.

Since Rowson repeats his bearded view of the matter again and again, I am looking forward for examples in his forthcoming book on Homosexuality in Classical Arab Literature – maybe he will prove me wrong.