I'm not sure how you got your first assumption from the rest of your quotations.

"[the Urbit] "senate" can do whatever they want to my data"

No. The urbit senate can do nothing with your data.

Your server holds your data. It is not distributed on the block chain. It is not mirrored by your peers. No one has any access to your data, except where you give them permission.

Your final quote refers to the power the senate of galaxies has to manage the address space. (currently limited to 4b personal nodes. If scarcity becomes problem, galaxies can vote to increase availability.)