if buck is buying a fixer upper house, then we might see the house getting repaired in tandem with his life. so as the house becomes inhabitable, furnished, and so on, we see buck growing as a person and establishing those roots oliver mentioned.
he's quite literally laying the foundation for a home tommy could realistically live in. because if it's a big, spacious house more so in the suburbs, then it'll have room for tommy. because i totally see tommy living in a somewhat cramped house in the city where maybe he's starting to outgrow it or needs more space. he seemed pretty impressed with buck's old apartment having all that room.
by the time tommy and buck reach a point where buck asks (again) f he wants to move in, tommy's finally going to say: "i thought you'd never ask." and we'll get domestic bucktommy.