While argument from authority
does make sense in a social/political context which functionally defines correctness in terms of authority of appointed office, I'm sure it wouldn't be lost on any seasoned lawyer that it still constitutes a fallacy when it comes to the merits of the argument alone. Similarly no one would know better than a lawyer the distinction between the authority of an opinion and its merits -- or to get less meta and back closer to the specifics of the opinion and surrounding arguments, the fact that multiple arguments can be reasonable and multiple policies might well be not only a side effect but the expected and even perhaps
desired outcome of public processes from court decisions (this one obviously different from the one it overturns) to elections.
And part of the point of institutions like courts is that the reasoning is subject to public review and discourse, both institutional and social.
I'm making a specific response to shortcomings apparent in the argument -- the opinion seems to treat the fact of differing interpretation of law or differing policy goals between different executive administrations to be some kind of bug or worse a surprise, when it seems entirely reasonable to expect it as a feature, one that certainly shouldn't be surprising to someone whose whole career (and indeed, features of this very decision) turns on the interpretive range often present within the law.
If you have specific commentary indicating how experts from a conlaw round table might engage this response, by all means, don't "just let slide", enlighten all of us in the course of doing the work that people genuinely combating Dunning-Kruger might do by elaborating on what, specifically, is overlooked in the response or missing from its counterargument.