Bullshit.
If Ruth Bader Ginsburg, who is stupid, dies in 2020 under a Republican Senate, let's just list the pressures that will work against Grassley's newfound belief that 25% of the time, presidents should be prohibited from filling Supreme Court vacancies.
1) Ideology. Remember that every single politician in the country is an "attitudinalist." That is, they believe "the attitudinal model," which states that judges are ideologically-motivated politicians in stupid costumes. Refusing to move a Supreme Court nominee would mean giving up a definite confirmation in exchange for a possible confirmation. No ideologically motivated politician would do that.
2) Partisanship. Grassley would face pressure from McConnell, whose commitment to the no-confirmations-during-election-years principle, adopted when Scalia died, was always obviously bullshit, and from the Republican electoral base.
3) Trump. Grassley would face intense pressure from Trump, who would never tolerate giving up a Supreme Court appointment. Trump might even... [gasp]… tweet mean things about Grassley! Heaven forefend!
Is Grassley's commitment to the no-confirmations-during-election-years principle really so deeply-felt and intense that he will withstand all of that? Obviously not. Remember, of course, that Mitch McConnell pulled the rule out of his ass as an excuse to block any Obama appointment to replace Scalia. Nobody had ever heard of the rule before because it never existed before, and nobody believed the principle then or now. It isn't a principle that anyone believes.
But let's say Grassley did. Is he the type to have a backbone and withstand partisan pressure when the winds blow in the other direction? No. What about a belief that he actually once had, for real? Like, that everyone should be required to buy health insurance because otherwise, they are spreading the cost to everyone else when they wind up in the emergency room? Yeah, Chucky used to argue that one. Did you remember that the individual mandate was the Heritage Foundation's response to "HillaryCare?" Then, the partisan winds changed, and suddenly, the individual mandate became the worst infringement on individual liberty ever. Chucky went with that, and even started spreading lies about death panels during the 2009 and 2010 healthcare debates.
Add Trump to the mix, and do you really think Grassley can stand up to that? No.
If there is a Supreme Court vacancy in 2020, along with a Republican Senate, Trump will fill it, and Grassley will go along. So, what is Grassley doing now? Well, if there is no vacancy, then there is no harm by saying that he'll adhere to that bullshit rule McConnell made up in 2016. Cheap talk isn't just cheap. It's free! And if there is a vacancy? What then? Well, have you noticed any of these people demonstrate the capacity for shame? Notice my reference to healthcare. The party, Grassley included, shifted from treating a mandate to buy health insurance as a cornerstone of healthcare reform to the worst thing ever. Was it idiotically hypocritical? Yes. Did they pay a price for it?
No. So why would any of them think that there would be any cost to confirming a Supreme Court Justice in 2020?
Grassley is full of shit. Guaranteed.
PS: Notice that I'm just reading the text. I'm not watching body language, or anything. Heidi Heitkamp had to watch Kavanaugh with the sound off to vote against him. I call bullshit on this method. I just look at facts, and the fact is that Grassley is a fuckin' snake. There is no self-presentation he could ever manage that would make him convincing, given the facts. Stop thinking you can read people. You can't.