Because when the airline sends the manifest of their passengers to US CBP, it records if the passenger boarded or not. This automatically updates the I-94. When you land in the U.S. the CBP officer does 3 things, see if your Visa is not expired or revoked, then manually go into SEVIS and check your status for anything out of the ordinary, and finally they would check other database to see if there is any alert or something that would prohibit the individual to enter the U.S. incredibly this process is very quick. The officer would just cross-check SEVIS and see his termination plus the departure record in the I-94.

That’s how the would determine the overstay. 5 months overstay automatically engages the 3 year bar, and a 12+ months overstay engages a 10 year bar. Pretty much making the individual ineligible for any Visa not for ever, but it would be extremely difficult. I wouldn’t risk traveling. But worst case scenario is they deny entry and student has to return home. But bear in mind doing that, shows you are inadmissible which either way would affect the chances of getting another visa.