Why is that! Because it doesn't agree with you?
Why is it not infallible? Because it doesn't come directly from the pope, using his papal authority, nor does it come from a council teaching, with unanimous assent from the current magisterium. Secondly, to be fair, Fr Feeney is also not infallible. And no one on here would say he is. Neither is any individual Church Father, nor Doctor, nor Saint. Or bishop, cardinal, priest, or pope (unless such pope is speaking ex cathedra on faith and morals).
Secondly, I take all books with a grain of salt. There's so much modernism out there, even in the 20s, 30s, 40s and 50s - you cannot blindly trust a book just because it was pre-V2!
So where do this leave us? Back at square one. "Outside the Church there is no salvation" and "Unless a man be born again of water and the spirit he cannot have everlasting life."
To answer the question "Can a non-catholic be saved?" the answer is simply, "no".
To answer the question "Can an un-baptised catechumen attain heaven?" the answer is "no". They could make it to limbo if they were justified.
The answer is simple because Church teaching is simple and Christ is simple:
"But let your speech be yea, yea: no, no: and that which is over and above these, is of evil." (Matt 5:37)