Assume you were a Baptist who actively avoided everything Catholic precisely BECAUSE it was the Whore of Babylon, the tool of satan, and you wanted to avoid all evil and cling only to God. Thus, whenever anyone tried to explain the Eucharist to you, you would hold fingers in your ears and shout loudly.
When you heard a Catholic quote Scripture, you would instantly remember the devil doing that to Christ and reject it out of hand, lest you be taken in.
Can such a person get into heaven?
Most assuredly YES!
Precisely because you were doing your best to stick close to God, you would - in this situation - be unable to access the truth. Consequently, you wouldn't be held responsible for the truths you COULD NOT KNOW and the truths YOU COULD NOT LEARN.
This sounds ridiculous to me. So when God desires to save a particular Protestant, and He sends a Catholic person to witness to that Protestant, and the Protestant responds by shouting "la-la-la" and shoving his fingers in his ears, God will still save that Protestant based on his stubborn adherence to an heretical sect and his refusal to listen to the Gospel, as if the Protestant's own voluntaristic efforts were enough to merit him salvation? That is patently absurd.
What a strange and confusing manner for God to behave in! Surely, if He wanted to save the Protestant, He could have just given him the grace to see that the Catholic faith was the true faith. Why all the slight of hand, especially when we consider that even if the Protestant could merit salvation by rejecting the true Church, he would still be saved in and through the true Church, and his prayers would have efficacy only through the Mass and the Eucharist that he belittles? Such a bizarre display would only serve to weaken the Church's witness and exalt personalistic efforts as the real path to salvation.
I also agree with stevusmagnus that it strains the bounds of credibility to suggest that Catholics will be damned for not effectively teaching the Eucharist to the Protestants, but the Protestants will be saved by their steadfast rejection of this doctrine. That's a real jaw-dropper.