I'm not so sure that getting less from another team (if it were to happen) is so bad considering it would be better than trading to the Lakers whom are in their same conference.
Trading him to a team in their same conference shouldn't be a big deal because they will be rebuilding anyway.
I understood the Spurs not wanting to send Kawhi to the Lakers because there was a chance they could see each other in the playoffs. Plus, Pop has deep hate for the Lakers because of all of the playoff battles.
But for the Pels, that would be a few years down the road. So, they should be focused on getting the best offer, no matter who it's from.