Getting back on topic...
1. It's not necessary to believe that OT saints were baptized. Some saints theorized they were, either in Limbo or being raised from the dead. Either way, it has nothing to do with BOD, nor is it provable, nor is it required to be believed. It's irrelevant for this discussion.
2. BOB is not the same as BOD. All the Church Fathers described BOB as being the sacrament, so really, there shouldn't be any BOB discussion in the context of BOD. They have nothing in common.
3. If one wants to believe in BOD, it is not heresy, provided that....
a. They believe in the requirements set out by St Thomas, St Bellarmine, which means it ONLY applies to
b. Formal catechumens taking formal classes to enter the faith.
c. Follow the guidelines of the Holy Office's letter to missionaries in the US, which states that there is minimum requirements of belief,
d. which agrees with St Thomas that for anyone to be baptized, they must AT MINIMUM, understand/accept the 2 doctrines of:
e. the Incarnation and the Trinity.
4. The conclusion of this is both simple and profound:
a. Any pagan who does not know of/accept the Incarnation/Trinity, cannot receive BOD.
b. Any muslim/hindu/jew etc cannot receive BOD, because they reject the Trinity and also that Christ is God and became man.
c. Any person who wishes to receive BOD would have to REJECT THEIR FORMER "RELIGION" FIRST and then decide to become a catholic, taking classes.
5. The notion of "implicit faith" is 1,000% heretical and it is found NOWHERE in any writing of saint, pope, doctor, etc.
a. It is a modern notion, pushed by heretics, the same heretics who infiltrated the Church at V2.
b. It is contrary to St Thomas, St Bellarmine and the Church Fathers.