ICE is not TSA. They’re both under DHS, but that’s where the similarity ends

Agreed, never said they were.

Further, not even the TSA can compel airlines to do cooperate in an arrest

If you read the report or watch the video in the link, Delta never had anything to do with the arrest itself.

If an officer of TSA or European Commission individual EU countries flight security asks an airline to defer boarding or step aside, they’re required, literally by law to do it:

“The ATSA gives the Transportation Security Administration (TSA) the direct authority to oversee civil aviation security, issue binding security directives to air carriers, and enforce mandatory compliance without prior notice or public comment.”

The answer is literally in writing and is agreed upon internationally.

Moral or not, agreeable or not, it is the law.