It's not completely true what you say about non of the top guilds being able to take kill him. We killed him on the very last try before the testing finished (Apex @ EU-Al'Akir). I'm sure quite a few other guilds were able to kill it aswell, since the fight was pretty easy.
Sparkuggz uploaded Method's kill to youtube on the 17th too, although perhaps they're not a particularly good guild to use as a benchmark for kills, it's certainly been done a fair few times.
Looks like an interesting encounter, I usually dislike add fights, but something about fighting a giant triceratops makes everything okay. Feels like it's been a while since we've been toe-to-toe with such a huge and mobile boss.