The only reason "heresy" is so terrible is precisely because Father Feeney was right.
If he was wrong, if baptism and the full Catholic truth aren't strictly necessary for heaven, then the whole thing is a paper tiger. Who cares about "heresy"? Truth becomes optional, God's commands don't really matter. You can get to heaven without the Catholic Faith, and without Baptism. None of it matters.
Yet here they are, loudly condemning "Feeneyism" as dangerous heresy while insisting you don't even need the truth to get to heaven. That contradiction is pretty glaring.
You seem to believe that between the false doctrine of Vatican II that says everyone goes to heaven and between the Feeneyite position there is no middle ground.
I would be greatly surprised if even 1% of humankind could qualify for baptism of desire. It is quite obvious when looking at the society around us that most people do not obey even the most basic principles of Natural Law, such as not committing or abetting infanticide.
God's commands matter, of course and the full Catholic truth matter. However, it is very difficult to cross a line to know exactly where there is no possiblity for invincible ignorance at all.
You should remember that, humans are fundamentally inequal at birth and in the eyes of God as well. That includes heaven and hell as well. The glory of a man who barely escaped hell will be far lower in heaven than the glory of a man who was virtuous during his entire life. Likewise, the worst sinners will suffer far greater torments than others.
How could anyone want to settle for being the lowest common denominator? And even that is risky, as God said He rejects the lukewarm.