and thanks to idiot who went with that public (GM involved) he got perma banned and glitch was fixed
when we (friends of me & me myself) went to instanced epl (naxx) around or before day when this went public we managed to get there (back then levi climbing was still on) to get on highest mountain and get in as combo of some tankish class, mage & priest & we landed near loatheb's room.... so we went fight with him - strangely he didn't 1 shoot us but it took him few mins to get us down...
later on i went solo there and landed on some platform with big patrolling spiders, strangely it was easy to kill them they did drop few silvers but coulnd't farm anything that would point that naxx40 loot table was still on
if you'd go through pics which i've psoted above - you'd notice that in "northrend test area" 60s can be found there... as far i know you can't skip level requirements for raid dungeon so the conclusion would be that this place was there since vanilla
http://imgur.com/a/XGbBu#58 - there were even mobs there xD