I am no expert, but here's Michael Kulikowski's argument quoted from the wiki page on the debate:

[Heather] is right to try to deduce governing apparatus from the actions that kings and chieftains were able to compel their followers to take. This approach, more than anything, goes some way toward justifying his assertion that a broad class of nonaristocratic "freemen" warriors must have existed in many of the barbarian cultures of the first half of the millennium. Yet to claim the point proved and build further hypotheses upon it is not legitimate; he comes perilously close to recreating the old, volkisch notion of an inherent “Germanic” belief in freedom. Throughout, in fact, Heather makes the tacit assumption that evidence from any “Germanic,” “Celtic,” or “Slavic” group can be used to analyze any other “Germanic,” “Celtic,” or “Slavic” group—in other words, that linguistic identity and socioinstitutional behaviors go inevitably together. [...] a great many historical comparanda would support a model that he ignores — that the Goths were formed from a large number of indigenes and a small number of migrants under the pressure of Roman imperialism, and in the shadow of the Empire.[31]

And more:

Kulikowski charges that old German nationalist and even Nazi influences continue to influence scholarship on the Goths up to the present day, particularly through the theories of Gustav Kossinna.[19] He considers much of what is written about Goths to be "Germanist fantasy" derived from this legacy.

This isn't exactly what I would describe as a debate "blessedly free from nationalist squabbles"

https://en.wikipedia.org/wiki/Origin_of_the_Goths