How is it 50%? What percentage of the time to you think the Lakers pick in the 2-5 range next year?
Boston structured the deal as they thought that either the Lakers pick or the Kings pick would be a top-5 pick. They were worried, justifiably so, that the Lakers would not tank next season and wanted some protection to still get a top pick, which is why the weird protection in order for the Kings pick to convey.
If the Lakers add Paul George this year, then you can forget the #1 pick equity next year and may even forget a top-10 pick next year. That leaves the Sixers with a 10+ pick next year and missing the Kings pick the year after (unless it is #1).