Interesting. My D21 is BME (JHU class of 2025) and no she didn’t need to enroll any sooner than normal.
When you say your son received a spot did he receive 2 Admissions? One would have been from the college and the second from the School of Engineering. If that is true I’m not sure why they would take it away without clear reason why. During Admissions those spots are allocated. That makes no sense.
The only thing I can think of is they have more acceptances than normal. All colleges tend to over admit knowing some students will NOT accept a spot (Yield protection). So that “could” be the reason. Sorry for the late reply. Hopefully you got an answer