I think the age policy is discriminatory - a younger recruit is more likely to resign and join another airline, especially from the low-cost ones. So a "bond" repayable over say 5-10 years would be more sensible.
The reason they specify 18-25 is simply because they have more applicants than places and it's a legal way (at present) to reduce the number of applications they have to consider.
People may argue that younger pilots will on average have certain advantages - but these arguments are exactly the same as used to justify other forms of discrimination in the past - which now that they are outlawed - seem hopelessly outdated.
As for IT being a career - most of my colleagues never really thought of it as one. In a profession with less change and more entry barriers - experience = kudos. At my age in a law career I might be a QC about now and earning serious money.