Actually, buggering an altar server before Mass and absolving him (though not required for him), or another priest and absolving eachother carries the sins of sodomy or fornication (depending on the sex of the server), abuse, violating sacred continence (not really a sin, but the Church thinks so) and, Excommunication for abusing absolution, Communion as sacrilidge (assuming that is thing and not a misreading of Paul). Sadly, this does not stop anyone from this conduct. Better to allow all manner of marriage, open it to clergy and abandon sacred continence.