The citadel denied quarian requests? Where did you read that? I didn't find it on any of the wiki.
Anyway, I think they didn't ban Quarian from settling on new planet. The wiki said that they're are looking for new planet to settle. It's most probably that the council's species is not willing to give up one of their planet for the Quarian. It's the same with Krogans. In exchange for their help, they give the Krogan planet from their own territory and perhaps give them all the support and help needed to settle on the new colony.
As for Bekenstein, perhaps it's nearby to the citadel not in term of actual distance but on the access through the mass relay. The mass relay near it might be just recently opened by human. So the citadel just recently know about the world and that in the context of within human territory.
Anyway, I think they didn't ban Quarian from settling on new planet. The wiki said that they're are looking for new planet to settle. It's most probably that the council's species is not willing to give up one of their planet for the Quarian. It's the same with Krogans. In exchange for their help, they give the Krogan planet from their own territory and perhaps give them all the support and help needed to settle on the new colony.
As for Bekenstein, perhaps it's nearby to the citadel not in term of actual distance but on the access through the mass relay. The mass relay near it might be just recently opened by human. So the citadel just recently know about the world and that in the context of within human territory.