no, it's not an IQ test. I mean, it's about as pure an aptitude test as you will find being used for university admission. All the others are subject specific, although they require only a small amount of existing knowledge, whereas the TSA is used for a range of different subjects because it is a test of your generic problem solving and verbal reasoning ability. I think the intention is to eliminate candidates who are statistically unlikely to do very well, which has the added benefit of making the interviews more manageable.
Plus, I can tell you don't know anything about IQ tests.