@mdri There is no reason to raise concern about the types of math questions on the GRE. Honestly, if a student is capable of doing higher level math, it shouldn’t be difficult to answer simpler math questions. Did he investigate the test at all before he took it? What was on the test shouldn’t have been a surprise.
https://www.ets.org/gre/revised_general/about/content/quantitative_reasoning
If he hasn’t looked into the breakdown of the PGRE and reviewed what types of questions are on the exam, he should so he can be prepared. There is absolutely no reason to go into the test and then be surprised by the types of questions.
Your son would be best served by working with his advisors at his school to decide where to apply. He needs to think in terms of what he wants his area of focus to be in grad school in addition to whether or not he is competitive for admission.