Oops also forgot to mention, it was a money-making operation for ICE too:

The fake university is believed to have collected millions of dollars from the unsuspecting students. An email from the university's president, named Ali Milani, told students that graduate programs' tuition is $2,500 per quarter and the average cost is $1,000 per month.

"They made a lot of money," Reddy said of the U.S. government.

The local division probably had a deportation quota they didn't have a chance to hit, so they created a situation where they could reach the quota.

IIRC normal cops do the same as a matter of course.

Bored sociopaths who need to justify their employment.