You're right about it being tied to emotion. It's a hard thought to realize that my Lutheran grandpa is in hell, given that he died suddenly; but that's the grave reality of the situation here. A reality which has been effectively lost on so many "Catholics" these days who have grown lukewarm and complacent with the "nice" sentiment that non-Catholics are saved. It's precisely why almost no one evangelizes.
Yes, with sudden death, even if someone happens to be Catholic, yet an obstinate sinner, such as divorced and "remarried" (living in sin), there's always that sorrow. But we don't respond to that by claiming that Bergoglio was right and that one can be living in adultery and still be in a state of grace.
Now, as a Lutheran, your grandpa was likely validly baptized, so that does allow for the possibility (albeit very remote, naturally speaking) that he received some interior illumination and grace before he could no longer do so. Time is of no consequence to God. He can accomplish anything in a split millisecond of time, or can suspend time as needed. Various saints (invoking God's power) have raised people back to life so they could be baptized.
And even in the case of a Jєω, as in 2Vermont's father, God CAN easily provide both conversion and the Sacrament, sending an angel to administer it. St. Cyprian, who believed in "Baptism of Blood", stated that those martyrs receive THE SACRAMENT of Baptism. I know that the Dimond Brothers call this out as a error. But I'm pretty sure he meant exactly that. He said that the blood supplied for the water while the angels pronounced the words (of the form). So for him BoB was still the Sacrament of Baptism, except that blood was used instead of water. Of course, Trent dogmatically taught that natural water must be used for the Sacrament. But it's still interesting about what some Fathers REALLY meant by "Baptism of Blood," where for some of them it was not an exception to the necessity of the Sacrament but an alternate mode of administering it (with matter and form).
There's absolutely NO NEED TO POSIT Baptism of Desire even for emotional reasons. Only those who lack faith feel compelled to do so, with one of their arguments being that God could be prevented by "impossibility" from bringing the Sacrament to His elect. St. Thomas said of the pagan living in the jungle that, if they're properly disposed, God can (and will) send an angel if necessary to convert them. What's to stop Him? Impossibility? If Our Lord God taught us that one must be born again of water and the Holy Spirit, there's nothing that could possibly get in the way of making that possible for His elect. Even XavierSem who had been very much anti-Feeneyite, in the end, began to hold the opinion that God would bring the Sacrament to all His elect ... even if it meant using extraordinary means. What need is there to speculate about substitutes for Baptism when something would render its reception "impossible"? That's almost heretical, claiming that God is constrained by impossibility. There's this general slur against Feneeyites that we believe that God is limited by the Sacraments, where it's really they who presume to limit God ... with "impossibility". We simply believe that Our Lord will keep true to His word. If He stated that the Sacrament is necessary for salvation, then you can be sure that He can and will get it to His elect.
I forget which saint it was, but there was a devout (apparently Catholic) woman who regularly received the Sacraments and then died. It was revealed to the saint that the woman had not been validly baptized. So he raised her back to life in order to baptize her. While back, she stated that she had been without her "wedding garment". That harkens of course to the parable of Our Lord in which He explained that those who show up to the banquet without their wedding garment will be cast out.