You've got Steve Gould and others with unassailable credentials claiming that mutations cannot produce new species:
"A mutation doesn't produce major new raw (DNA) material. You don't make a new species by mutating the species."
Stephen Jay Gould, Prof of Geology and Paleontology, Harvard University "Is a New and General Theory of Evol. Emerging? Lecture at Hobart&Wm Smith College,Feb4,1980
To the best of my knowledge however, neither Gould nor anybody else offers up anything to replace the idea of mutations and selection driving evolution. The punk-eek crowd uses the term "speciation event" without specifying what it means other than for the other mumbo-jumbo term "allopatry" which any reader would take to mean via mutations. The Marvel comic books use the term "Shazam!" for the same sort of thing.
That means that Nilsson's version of such mumbo-jumbo is every bit as good as anybody else's.
Now, during the first decades of the last century, REAL tests were conducted bearing on the possibility or impossibility of macroevolution. Fruit flies breed new generations every other day so that running such tests for decades will involve more generations of fruit flies than there have ever been of anything even vaguely resembling humans on this Earth. Moreover, they subjected those flies to everything in the world known to produce mutations and recombined the mutants every possible way. All they ever got were sterile freaks, and fruit flies.
That was because our entire living world is driven by information, and the only information there ever was in that picture was that for a fruit fly. When RNA and DNA were discovered a few decades later, the reason for the failure of those tests was known.
"At that moment, when the DNA/RNA system became understood, the debate between Evolutionists and Creationists should have come to a screeching halt.
I.L. Cohen, Researcher and Mathematician Member NY Academy of Sciences Officer of the Archaeological Inst. of America Darwin Was Wrong - A Study in Probabilities New Research Publications, 1984, p. 4
Beyond that point in time, there is no reasonable way anybody should have gone on believing in evolution.
"A mutation doesn't produce major new raw (DNA) material. You don't make a new species by mutating the species."
Stephen Jay Gould, Prof of Geology and Paleontology, Harvard University "Is a New and General Theory of Evol. Emerging? Lecture at Hobart&Wm Smith College,Feb4,1980
No I don't. I have your uncited source, creationist Luther Sunderland, a man with a rich record of misquoting evolutionists, or presenting snippets of their views so widely out of context that their meaning is inverted fully 180 degrees, saying that Gould said that.
Even if it were an accurate quote (it reads like a paraphrase of some sort) it's too short and isolated a snippet to determine either the actual point Gould intended to make, or the body of data upon which his point was based. Naturally, neither issue is of interest to creationists.