Could be one of the most compelling arguments I've seen in a while. Who knows? Perhaps Raxxla is the Guardian's home world?
"...and all that’s in those Universes in the way of bounty, and treasures, and aliens, and life..."
I wouldn't necessarily say it is the Guardian homeworld, but based on that quote, to me, it seems Guardians, Goids, and humans are able to co-exist there? It says, aliens, plural, and life, as in human? I'm assuming civilizations had a means to get in and back out.
Also, when the Thargoids and Guardians were at war with one another, Guardians tried to understand the Thargoids in an effort to being able to communicate and bring peace, but have we tried to use Thargoid items (Artifact, links, etc) at the guardian sites/ruins?