If we get an FA (Hayward/Griffin) we can still trade for Butler/George afterwards. That gives us a team that can match up with Golden State.
If we trade first, we cannot get an FA afterwards (and likely won't have the assets to trade for an additional piece.)
"Waiting for FA" is the only way this team can hit its ceiling. That's why we won't be making a Butler/George trade unless the price is extremely cheap.