Hi there,
You are right from the subjects side, however a lot of unis will take in students on a foundation degree only on the basis of their grades in what they are currently doing. This is because the point of a foundation year is to give you the underlying knowledge needed for a certain degree no matter what subjects someone was doing previously, so it shouldn't be a problem as long as you fit the current grade requirements.
Just to double check though, you can email universities to ask about their course entry requirements and see if they'll accept him onto a course with a foundation year.
If you have any further questions feel free to ask, otherwise wishing you two all the best,
Ams - LJMU Student Rep