You can accept the apology and still decline the old seat next to them.

An apology and a return to how things were are two separate transactions, though they usually get presented as one. Forgiving somebody means you are no longer carrying it around. It does not oblige you to hand back the same access, because trust is built out of a record over time, and a record does not reset because of one good sentence.

You can be warm and still keep some distance for a while. Be civil, be pleasant, and let closeness return on the evidence. If somebody insists that real forgiveness means everything goes back at once, that is a request for access rather than peace.