Basically, LIV needs the International Series on the Asian Tour so players can earn world ranking points. They can't just make them optional because they need the highest ranked players to play to stengthen the field and increase the world ranking points available.
Of course, the giant elephant in the room is that by the time these events roll around, the top players OWGR's will have fallen so far that it may not matter anyways.
The No Laying Up guys have also been talking about changes to the OWGR which either have just recently been made or are about to be made (I forget which) that will mean having just a few star players in a field won't give it much of a boost; it's going to be the depth of a field that matters more than its top-line stars. Which will also go some way to curtail the impact of some of the autumn/winter exhibitions with small, elite fields - I'm thinking particularly of the Hero World Challenge, which for some reason awards ranking points and in the past has awarded quite a few of them because everyone in the field is excellent, but it also has only 20 players in it and going forward will be punished accordingly on that basis.
I call bullshit. They aren't turning away top 50 players.
FWIW, that doesn't seem to be a LIV quote - that seems to be a Golf Digest assessment from "multiple managers from different agencies". If that story is true, and LIV will shortly be entering a consolidation phase and looking to market a stable group of 48 players (and 12 consistent teams) to the world, then a) it makes sense that the Saudis might turn the tap off, at least for a while, and b) the LIV vs. PGA Tour dynamic may settle down quite a bit as well, at least in the short term. The existential threat to the Tour is the worry that anyone might bolt to LIV at any moment; if the number of places LIV is looking to fill really is approaching zero, and the offers being made to players are "significantly lower" to the point that the Tour's rewards on offer actually seem competitive, then the Tour can maybe take a deep breath and consider it's own medium-to-long-term strategy instead of having to be 100% reactive.