Don't know if I fully agree with all of that. He has an image problem, true, but more because in my opinion of who his mother was and how he became a full wizard in the first place ...
No, there's (much) more to it than that.
It's unclear just how big that "more" is, and the exact shape of it; but let me remind you:
Consider the Council's POV:
1/ if Harry's story is true -- killing DuMorne was self-defense after the former Warden sent a summoned demon after him -- then Harry was raised by & apprenticed to a warlock; specifically,
he was trained as a warlock (not as a WC wizard). And we know this actually
is the case, because Harry keeps showing up with weird bits of wizardly ignorance unsuited for a full WC wizard (types of lycanthrope, 3-queens model of Summer/Winter courts, "Conjuritis," etc)... but with a really-outsized suite of combat-magic. And if his story isn't true -- DuMorne didn't attack first, it wasn't self-defense -- then he killed DuMorne in a full-blown 1st-Law-breaking warlock act.
Either way, that pre-WC background is a HUGE piece of Harry's "image problem;" it gives the overwhelming appearance of "whichever way it happened, he's still a warlock."
2/ Speaking of Harry's "outsized" combat power -- it's
REALLY outsized, frighteningly-powerful: Harry scares entire combat-platoons of Wardens. Beginning -- as a barely-trained teen -- by taking out a fully-trained senior Warden, he moved on to vampires (all the big Courts), lycanthropes of various stripes (including the incredibly-tough Loup-Garou), on up to heavyweight Fae and thence to the Summer Lady. It's remarked that before he turned 40 he had seen more combat that most wizards ever saw in their lives, and defeated more-powerful foes than most ever defeated... and he's still in the "dumb kid just figuring stuff out" phase of his career!
That's terrifying.
3/ When Harry first met McCoy's Sr-Council allies in the parking structure, one of them reminded McCoy "you know what he was meant to be." Now...
we don't know "what he was meant to be." Just the Big Gun in a warlock's private brute-squad? Or something else, something more... a reference to his mom's "Starbabe" plan? And what about the reference to a "Destroyer" in the Morgan-POV short
Journal (we don't even know what a "Destroyer"
is; but presumably it's something known to (at least some of) the Senior Council)? But there's something about Harry, about his origin and/or early training, that makes him inherently problematic and worrisome, to those who know.
4/ His overall attitude of disrespect for the WC and their authority paints him in a proud and arrogant light; more than one senior wizard has remarked (when Harry complained about the stifling WC rules) that Harry is unaware of the horrors unrestrained wizardry has unleashed (and every time that happens, read the subtext there of
Harry having pointed-out to them the inadequacy of his training, how Justin skipped the history and the "why" and the Laws, in favor of
m0Ar POWER!