I assume the secret service made the decision to rent, and weighed cost, location, etc as factors.
I would have a problem if it looked like the rent was out of line with the market…
According to the link it was the SS’s choice – they’d been renting a different space and chose to take advantage when the old tenant moved out.
Hmmm… we’ve got a granny flat. I guess if I become president I could rent it out to the secret service.
The problem I have with the linked post is that it suggests Biden should give it to them for free, even though he had a paying tenant in it previously.