From the blog entry you linked to:
"[a member may not] Create a Gamertag or use text in other profile fields that may offend other members. This includes comments that look, sound like, stand for, hint at, abbreviate, or insinuate any of the following: profane words/phrases, sexually explicit language, sexual innuendo, hate speech (including but not limited to racial, ethnic, or religious slurs), illegal drugs/controlled substances, or illegal activities."
(Emphasis mine). So the only gamertag that would be appropriate would be an unpronounceable string of consonants with no numbers, as such numbers could be mathematically related to 666, 420, 911, or some other number that a person would find offensive? Please, Microsoft, for the good of mankind, can we just let people be offended?