No, on the contrary, the "arguments for [BoD]" are very weak.
Majority of Church Fathers rejected BoD. We had one (St. Augustine) who tentatively floated the idea in his youth but then later retracted it, and St. Ambrose, who was not speaking about something that could save, but merely wash from sin. St. Ambrose elsewhere explicitly states that a catechumen, regardless of how many virtues he might have, cannot be saved without the Sacrament of Baptism. Meanwhile, about 6-7 Church Fathers explicitly reject the notion.
So there's no evidence from the Church Fathers that BoD was revealed.
Now, absent that, the only other way that something can be discerned by the Church as revealed, is if it were something that logically and necessarily followed from other revealed truths, but no such argument has ever been offered. Instead, there's an "appeal" to the "authority" of St. Augustine and St. Ambrose (except that the former only held the opinion very tentatively and then retracted it, while the latter's opinion is highly debatable) -- and are the other 6 Fathers who rejected it chopped liver? -- and appeals to emotion ("it would seem to harsh"), or the argument of St. Thomas that the Sacraments have visible and invisible aspects (OK, but that doesn't mean that one can be had without the other ... and that is manifestly NOT the case with some of the Sacraments, especially those entailing the reception of a Sacramental character, of which Baptism is one). There's been no argument that shows BoD follows necessarily from revealed dogma/doctrine.
So how can it be "heretical" to deny what is clearly nothing more than theological speculation and which clearly was not revealed by Our Lord through the Apostles (otherwise, many Church Fathers would have taught it with authority).
Finally, one cannot give the "assent of faith" to a concept or a phrase. We assent to propositions. It's strange that there are as many definitions of what BoD is, how it works, what it supplies for and what it doesn't supply for, as there are proponents of BoD. I find it nowhere defined in the Magisterium so that I know what to believe about it. In fact, the greatest common denominator of all BoD theory is ... the Sacrament of Baptism is not necessary for salvation, but, you see, that's heresy.
BoD is nothing but emotional speculation. Even St. Robert Bellarmine succuмbs to this, holding the possibility for a catechumen (not, only a formal catechumen) to be saved by BoD because the contrary "would seem too harsh". Adding to the confusion, does BoD apply only to catechumens? St. Robert certainly thought so.
BoD is also predicated upon a heretical premise, namely, that God could be constrained by impossibility from bringing the Sacrament to His elect (the reason St. Augustine fiercely rejected BoD later in life). BoDers claim that God cannot be constrained by the Sacraments ... and yet somehow hold that He can be constrained by circuмstances that render the Sacrament "impossible". There's absolutely no reason BoD is necessary. When God can EASILY bring the Sacrament to His elect, why would He not do so? We have stories of saints who raised people back to life in order to baptize them. We have the OT just rising after Our Lord's Resurrection in order to (according to some Patristic tradition) be baptized, so they could enter the Kingdom of Heaven. God could easily send an angel, not only to preach the faith, but also to baptize. Or He could have them baptized when their bodies are raised back to life at the final Resurrection.
There's no evidence whatsoever of BoD having been revealed, and there is absolutely NO NEED for it. Only purpose it has ever served has been to undermine faith in the dogma that there's no salvation outside the Church. Without BoD, you'd never have gotten Vatican II, since the V2 ecclesiology is predicated upon finding a mechanism to get non-Catholics into the Church.