Has anyone found a way to open the second door in the Dragon's Lair in Dragonspire?

I suspect it may open if the dragon is killed before the door to the mavin is opened. Thus given access to Brimloch Roon without allowing you to take the sword. DWB seems to have tried to cover all eventualities, for example (1) allowing you to win with the lich's staff if you fail to get the mavin itself and (2) having a spare suit of Dragon Armour in the treasury in case you kill Freyedies before he processes the dragon ore.

Just wondering.....

Yet another interesting ponder.
I figured it was just a dragon sized door for dragon use exclusively when he wished to enter and exit his lair. Now, if it were possible to split your party - would you want to find out if the Dragon could be flying over the Shire breathing fire on half your party while the other half had tea with him in the Spire??

Wyv