It's worth nothing that this change happened before the questionnaire was instituted. (The paper referenced in the article was from 2006, I haven't dug enough to find a date for when this change was made, but the narrative in the article also establishes this act as happening in the '00s.) Additionally, from the Conclusions:
"Reweighting was based on data collected from incumbent ATCSs who took AT-SAT on a research basis; some of these employees achieved overall scores less than 70 (that was one of the reasons for the reweighting effort – a belief that incumbent employees should be able to pass the entry-level selection test)."
I don't think this proves that the update to the test was good or bad in overall competency, but I do think it's worth investigating if the test should be updated when existing employees are unable to pass.