A previous poster asked "what does pupil premium actually do? What is it spent on?"
I have 2 DCs on FSMs (and therefore they get pupil premium) at a super-selective grammar school. At their school there is no queue-jumping because of FSMs, so the numbers who get in, who are eligible for pupil premium are tiny. Only 19 children out of 900+ have at any time in the last 6 years been on FSMs!
Every term, the Pupil Premium Manager meets with my DCs, reviews their performance and discusses with them where they would like the money spent. DC2 has additional needs. His needs are not so serious as to warrant a statement (although he's on the SEN register), so the school does not get any extra SEN money for him; instead they are able to spend the PP money supporting him. This includes paying for one session a week with a TA; after-school classes with a teacher etc.
DC1 does not have additional needs and achieves pretty well, so it has been harder to find things to spend the money on. At one point the school asked me if I would like it spending on a school trip, and I said no, because I would rather the school had the money to spend on teaching. This year he is doing his GCSEs and the school provided study/revision guides for him and also lunchtime revision sessions one-to-one with a teacher in a subject he is finding difficult.
Even if the school adjusted their admission criteria so that FSM children were prioritised, I cannot imagine this would make a massive difference to the numbers passing the test. As it's a super-selective, DCs can (and do!) take the test from anywhere in the country; so you do have to be very bright to stand any chance of passing. A whole busload of 50 children arrive every morning from a city 45 miles away. Other people living further away move house, if their child passes. One family even sent a note round the school asking if any local family would be willing to be paid to have their DC live with them Monday to Friday, to save the child travelling 60 miles there and back every day!
The OP's ire should, I think, not be directed at the very few FSM children this policy will probably benefit; but at the fact that there are so few GSs left that everyone is desperate to get in.