"PLME Candidates and Early Decision
An early decision applicant who indicates a desire to be considered for entry into the PLME may be admitted in December to both the College and the PLME. However, some students may be selected for admission to the College but not the PLME. The Office of College Admission realizes that these students may not wish to be admitted to the College under a binding early decision program if they are not also admitted to the PLME. Hence, the office asks all PLME applicants to indicate whether they wish to be considered under a binding early decision plan if they are not admitted to the PLME.
Those who answer "yes" that they want to be considered as an applicant to the College under its binding Early Decision program but are not admitted to the PLME, may be admitted, deferred or denied by the College. Those who are admitted to the College are bound under the early decision agreement; they may or may not be admitted to the PLME in April. Those who are deferred from the College may be admitted into the PLME in April under a nonbinding program. Those who are denied will not be considered again.
Those who answer "no" that they do not want to be considered as an applicant to the College under its binding Early Decision program and are not admitted to PLME, may be deferred or denied by the College. Those who are deferred by the College may be admitted into the PLME in April under a nonbinding program. Those who are denied will not be considered again."
Admission | Program in Liberal Medical Education
The last paragraph reads to me that if you don't want to be bound be the ED agreement, then there is no way that you will deferred/rejected by PLME, yet admitted to Brown during the ED stage. In other words, the scenario you describe will never happen.