Can two humans with 44 chromosomes produce viable offspring?
The article says "both his chromosome 14s are stuck to his chromosome 15s" - meaning both his mom and his dad (46,XX,rob(14,15) and 46,XY,rob(14,15) had a Robertsonian Translocation which doesn't really result in the loss of any genetic material. The very small chance occurred which one sperm carrying the translocation chromosome fused with an oocyte carrying the other translocation chromosome.

So the genotype of the dude is 44,XY,rob(14,15)(14,15), meaning he's normal because he technically has all the genomic information of a normal human.

If he mates with a normal woman (46,XX), then the resulting progeny will have an extra copy of chromosome 15, resulting in trisomy 15, which is non-viable.

If one such 44 chromosome individual mates with another person of the same chromosomal arrangement, then probably a viable fetus would be produced if a translocation chromosome ends up with the same translocation chromosome from the mother. I wouldn't call it a new species per se because it still contains the genetic material from a human. For example, there are many humans with chromosomal abnormalities (I.e trisomy 21, XXY, etc...). Also the background rate of translocations and chromosomal aberrations in somatic cells is notable, so I wouldn't use this as a new species definition.