Because it's a genocide extension that's about to happen.
His message is a clear declaration to ethnically cleanse Gaza.
Correct. It's a civil violation, and increases the risk of deportation. Normally foreigners overstaying a visit don't immediately get deported.
The overstay consequence is that it leads to a 3-year re-entry into the US ban if the overstay is under 1 year or 10-year re-entry ban if it's over 1 year.
Either way, this really sucks for the couple. They most likely won't be able to have a life in the US anytime in the coming years.
Constitutional rights are based on personhood, not citizenship. Mahmoud Khalil's 1A rights were violated, plain simple.
https://constitution.congress.gov/browse/essay/artI-S8-C18-8-7-2/ALDE_00001262/
You have no moral leg to stand on. Barely any noticeable difference between you and Trump/MAGA in how you view Palestinians as subhuman.