To start, consider the ultimate source of this practice: it's neither the Muslim Brotherhood nor the Salafis; rather, as with most of Islam's perversities—from adult breastfeeding to pedophilia marriage—Islamic necrophilia is traced to the fount of Islam, its prophet Muhammad, as found in a hadith (or tradition) that exists in no less than six of Islam's classical reference texts (including Kanz al-'Umal by Mutaqi al-Hindi and Al-Hujja fi Biyan al-Mahujja, an authoritative text on Sunni Doctrine, by Abu Qassim al-Asbahani).
According to this hadith, Muhammad took off his shirt and placed it on a dead woman and "lay with her" in her grave. The gravediggers proceeded to hurl dirt atop the corpse and the prophet, exclaiming, "O Prophet, we see you doing a thing you never did with anyone else," to which Muhammad responded: "I have dressed her in my shirt so that she may be dressed in heavenly robes, and I have laid with her in her grave so that the pressures of the grave [also known as Islam's "torments of the grave"] may be alleviated from her."
What was Muhammad saying and doing? Perhaps his magical shirt would transport the dead woman to heaven, and his blessed body would protect her from the "pressures of the grave"? A more cynical—a more human—reading is that he stripped his shirt as a natural step before copulating; that he precisely, if not sardonically, meant the act of sex would "alleviate" the pressures of death from the corpse; and that the observers covered them with dirt for privacy and/or for shame.
This interpretation is given much more weight when one considers that the secondary meaning for the word I translated above as "lay with" is "intercourse," further demonstrating that the proposed Egyptian law is, in fact, based on this hadith: after all, the Arabic root-word used for "intercourse" in the phrase "farewell intercourse" is derived from the same root-word that Muhammad used to explain what he did with the dead woman (d-j-'). As if this was not enough, necrophilia finds more validation in Islam's legal texts. For example, according to al-Sharwani's Hawashi, "there is no punishment for having intercourse with a dead woman" and "it is not necessary to rewash the dead after penetration."
Incidentally, this issue of "death-sex" far precedes Egyptian parliamentarians. In fact, I first wrote about this macabre topic back in 2009, based on an episode of Father Zakaria Botros, where he explored the perverse sexual habits of Islam's prophet Muhammad (see here). Interestingly, when that episode first aired, many Muslims were livid, denying the existence of the hadith, and renewing calls to assassinate the priest for trying to "defame" Islam: yet here it is, once again—only this time, the hadith is being passed into a "law," further documenting the existence, if not legitimacy, of necrophilia in Islam.
Which leads to another eye-opener: it is no longer this or that "radical" cleric, but parliament members who are, not merely acknowledging bizarre Islamic practices, but trying to implement them as "laws." (Perhaps this should be unsurprising, considering weeks earlier in Egypt, suit-and-tie wearing Muslim court lawyers attacked with knives a Christian defendant for supposedly "blaspheming" Muhammad.)
What else do such "parliamentarians" and "lawyers" have in store for Egypt and its neighbors? If this little known, ghoulish practice is being endorsed simply because of one arcane hadith, how much more support must Egypt's Islamist-dominated parliament be giving to those other ironclad teachings of Islam—for instance, Muhammad's unequivocal commands, recorded in hundreds of canonical hadiths, to fight, deceive, and subjugate all non-Muslim infidels?
When it comes to Islam, it is high time for the West to learn to connect the dots.