An argument relying on absolutes (see bolded) is rarely sound.
Even if one acknowledges that recruiting and other roster management aspects of being a CFB head coach are dramatically different in the pre- and post-NIL eras and that Sark is more advantaged in the current era, which I do agree with, that does not make his time at USC and UW totally irrelevant bases for evaluating his merits (and prospects) as a head coach.
But how about player development, game planning for upcoming opponents, in-game adjustments/management, coaching staff management and, last but not least, proclivity for vices and other things outside the football complex that could undermine everything the coach might be doing well within it. Those are just a few critical aspects that can serve as valid points for drawing valid apples-to-apples comparisons across both eras. It's fair to look at Sark's pre-NIL track record in these areas to make an educated assessment of his weak (and strong) points as a head coach and how that might be expected to translate to future W's and L's.
In sum, the situations are somewhat different in that recruiting and roster management have changed dramatically. However, the situations remain the same on many fronts - so the notion that they are "completely" different, or that any comparisons are invalid, is laughable.
If what you are actually trying to say is that NIL advantages will lead to so much of a talent advantage over our competition that any coaching weaknesses Sark has carried during both areas are mitigated, that is a fair argument. But that's not the argument you've actually made to this point.