The exact language of the April 15 resolution: “If a student accepts an offer before April 15 and subsequently desires to withdraw that acceptance, the student may submit a written resignation of the appointment at any time through April 15. Applicants are not required to obtain a formal release from the program whose offer they accepted, either before or after the April 15 deadline. Once applicants have informed the program that they are withdrawing their acceptance of the offer, they then can accept any other offers.”
It’s clearly not discouraged or even odd for a student to back out of an acceptance if they have specific guidance regarding that exact situation.