I've never run across an "implicit BoD"er who did not attempt to extend it to people who do not have the Catholic faith.
I don't believe in any kind of BoD, but if I were persuaded of it, I would be of the opinion that the intention to receive Baptism has to be EXPLICIT, as in, "I'm a catechumen and I intend to be baptized next Easter." I believe that St. Robert Bellarmine would hold the same opinion of it. votum is a very strong term, meaning closer to "vow" than "desire" (a term deliberately chosen to water it down). You can't "vow" to receive the Sacrament without believing in and intending explicitly to receive it. It's not enough to "vaguely desire" it somehow.