it seems to just be a bunch of D1 nostalgia. You'll notice the old music player, D1 chest models, some old "phone terminals", the swords and shields that were placed next to exotic terminals, presumably all the dead Ghosts the guardian has collected, the D1 Vanguard meeting table along the wall, that weird table from the Vestian Outpost, and of course some faction symbolism. I'm sure I missed some things, but those are all I could make out. I'm not sure if there's any specific reason it's hidden away, collapsed, and covered in debris, bugs, and moss, but I don't think there is any real significance to it, unless there's some time-gated lore card in there