If they can proven to be so. What employees do is then build a proxy for IQ tests that has some job related stuff. Math or logic puzzles could be used if they relate to CS topics. It's not just "find the next element in the pattern" but "find the next sorted item in a list" and so on. They could argue that "Well the employee could in principle be inverting binary trees all day at their job..."

I bet many involved in designing and setting the requirements know exactly how it works but they'd use veiled language and never put anything down in written communication.