Hello!
I just tried doing the quest from Harrison Jones in Grizzly Hills (crypt in troll ruins to the north-east), and after the big snake appears in the small room, the fire door re-appeared and I got trapped inside. I yelled and texted hordes in the area and nobody came. Then the unexpected happened: an alliance druid came, started the quest and freed me! I thanked him/her, got out, and tried to warn him/her (/go) but then the druid got trapped too! And hearthed out lol. So I waited for Harrison Jones to respawn, re-started the quest, attacked the snake and swiftly got out of the room (the snake followed me out) and done it! (easily soloable with my 75 affliction warlock).
So that's it! Now you're warned! Don't trust that guy!