It’s a psychological play that is politically motivated. Nothing else.
But for someone preparing their entire life to start a job, everything is up in the air now. They're not so privileged.
Both you and the parent are correct. It sucks for me. It is just a political play: his approval ratings have been slumping, this will help for a point or two.
Regardless of one's opinion on immigration however, suddenly creating an immediately invoked executive order with no warning, no grace period, and no plan for what comes next is reckless and will needlessly cause harm to many people who were just trying to do what's best for themselves while acting fully within the law and system as it exists (er, existed). It is a morally bereft and politically motivated action, which is to say, exactly what we should all expect from the narcissistic orange clown in the Oval Office.
There's been warning that something like this was coming for a while, and it's been broadly expected since the April 22 immigration halt order, given the way Trump had previously railed against the existing H-1B system as worker-hostile and the entire justification for the April 22 immigration halt was the threat to US workers from immigrants in the present crisis.
I think much more likely it’s a strategy to provoke a legislative solution. There is basically no reform legislation that can occur in 2020 without a major forcing function.