Sure (although Trump's legitimacy to be in the position to do this kind of stuff is also suspect, but that's just me looking from across the Atlantic) but that doesn't make things necessarily legitimate.
Musk being in a position to do this due to Trump appointment doesn't imply that this ought to be a case, or that this is proper. Thus critique.
Why is Trump suspect? This is the same argument made last time by Trumps side. He's legitimate, since there are no rules not allowing him (he's a natural citizen and well old enough), thus meeting all requirements. Is he a proper choice? No, but neither side offered any proper choice in a meaningful time and thus failed our nation.
Is Musk a Chief of Staff? A press secretary? Why no Senate approval?
He's a SGE - which is time limited, and needs no approval.
And has strict limits as to their authority which don't appear to be being followed. Is he the head of DOGE or isn't he? Depends on if it's a reporter or a judge asking.
Funny because everyone was stating his role in a way that doesn't fit that definition in public, but then changed to fit the definition when required in court.