Well there is no dispute here only facts, really: Shanti Baba used to work for Greenhouse Seeds, but left to join up with Mr Nice and become their in-house breeder. So he developed the Widow, and as such just has the best handle on it, and over the years he has managed to improve it time and time again, where others did not really succeed in as spectacular a fashion, even while working with the same genetics.
Shanti Baba is one helluva breeder, and I am yet to see a complaint about any of his genetics. So it's not about disputes or the others being bad copies, more about the fact that it is his intellectual property and his vision, so for that particular strain, he is most likely to give you the results you want or have come to expect from the Widow.
MNS Black Widow is probably the most frosty strain I have ever seen. Greenhouse had a few hiccups with their updates to it, it went a tad mutant and lost some vigour, not sure if they fixed that by now but I ran a WW from them and was NOT impressed.