Although I am somewhat critical of Underwood's claim that the male masculinity was not challenged by romantic poets, line 513 seems to be a reaffirmation of the masculine principles of control, strength, and protection.
This isle and house are mine, and I have vowed
Thee to be lady of the solitude.--
And I have fitted up some chambers there
Looking towards the golden Eastern air,
And level with the living winds, which flow
Like waves above the living waves below. (513-18)
Perhaps the vacillation between control and and passivity can be the key activity involved in the creation of the acrogenous subject. I know, for instance, that Sir Walter Scott's novels were viewed as an antidote for the feminization of the male subject, but it is also worth noting that all of Scott's heroes had qualities that one would not normally consider as masculine before the advent of Romanticism. The fact that Scott supposedly created the genre of novel known as the "historical romance" actually either reaffirms the notion of the androgynous subject or at least redefines our conceptualization of masculinity.
Underwood, Ted. "The Science in Shelley's Theory of Poetry." Modern Language Quarterly 58 (1997): 298-321.