[wat10000]

The rules absolutely change along with the President. The President has total discretion about which non-citizens are allowed entry. Just a few days after Trump took office the first time around, he unilaterally banned people from a bunch of countries from entering. If Trump told CBP to deny entry to anyone found making critical statements of him, that's probably legal and even if it wasn't the illegality probably couldn't be enforced. More likely, this is preemptive compliance, where either the agent feels emboldened to make this determination on his own, or thinks it's what the boss wants. Individual agents have free reign to deny non-citizens entry.