[quote=Allen Montgomery]The Invisible Man living in a girls' school and making multiple "immaculate conceptions" was respectful?
[/quote]
Yes. It is.
Adult sexual themes in and of themselves are not disrespectful. If the LOEG books are meant for an older audience, it's a perfectly valid theory of where the character might end up.
If you read the H. G. Wells novel, Griffin becomes a murdering paranoid, hell bent on world domination, through a maniacal "reign of terror." SPOILER... He's hunted, seized, assaulted, and killed by a mob.
If we are to assume he survived somehow, Moore's idea is perfectly valid. Rape is more about power than sex, he's a beaten, recovering wannabe world conquerer, possibly more damaged than before, in a remote, self-contained place, easily managed by him, a murdering paranoid. And any witnesses to anything odd are easily dismissed by the older staff. It fits well enough.