They are very restrictive with changes of status from B1/B2 to F1, and changing to F1 status (or any other nonimmigrant status) is not allowed unless the change of status was filed before the previous status expired. His B1/B2 status has expired and the visa is invalidated due to the overstay, so he is not eligible for a change of status. He must leave the US and apply at a consulate for the F1 visa.
PD: Jan 2003 (EB3 rest of world)
I-485 Approved: July 2007
I am a layman, not a lawyer. What I write here is not official or professional legal advice. In addition, my answers on this forum are specific to the scenarios discussed in each thread and should not be generalized to other situations.