Choice of torroid for output inductor of Two transistor forward in DER-484?

Hi,
In the DER-484 document, Power Integrations detail the design of a 280W Two Transistor Forward converter. This concerns the design of its output inductor using a powdered core torroid.

DER-484
https://ac-dc.power.com/sites/default/files/PDFFiles/der484.pdf

…On page 44, Power Integrations state that they choose a 77930 powdered core by Mag-Inc. Power Integrations expect it to have an inductance of 229.4uH at the DC bias current of 4.6A. They use 75 Turns.
Why have Power Integrations chosen the 77930 core?
Firstly, the 77930 core datasheet shows in a chart that its only for consideration up to 250 Ampere.Turns. Clearly, the actual ampere turns is 75*4.6A = 345 Turns.
Also, Mag-Inc have a “Kool mu” core selection chart on page 26 of the Mag-Inc Powder cores catalog. This allows you to put in the “L(mH) * i^2” value and read off what torroid is suitable. The “L(mH) * i^2” value is 5.99. Reading off from the chart, this means a 77586 torroid is suitable. The 77930 torroid doesn’t even appear on the chart.
Therefore, do you know why Power Integrations chose the 77930 Torroid?
Mag-Inc powder cores catalog:
https://www.mag-inc.com/Media/Magnetics/File-Library/Product%20Literature/Powder%20Core%20Literature/Magnetics-Powder-Core-Catalog-2020.pdf

77930 torroid datasheet:
https://www.mag-inc.com/Media/Magnetics/Datasheets/0077930A7.pdf

77586 torroid datasheet:
https://www.mag-inc.com/Media/Magnetics/Datasheets/0077586A7.pdf