I disagree. The resemblance here is much more striking:
Check the line of the nose, the sweep of the chin, the curl of the smile, and the slope of the brow -- not to mention the hair.
Hewitt has the wide-set eyes typical of Anglo-Saxon-Pictish-Celtic Brits. Harry has the close-set eyes and long nose more typical of the Hanoverian Germans and Scandanavians. Harry's grandfather Philip Mountbatten was German and Danish, and his father Charles is from the Saxe-Coburg-Gotha German royal line.
Hewitt's ears are flatter and his nose is shorter. His forehead is broader and rounder at the top, but Harry has the Scandanavian "horns" at the top of his brow. And, Harry's eyes are blue, as are his father Charles' and were his grandfather Philp's. Hewitt's eyes are clearly brown:
A recent article in the DailyMail showed Hewitt working as a groundskeeper in a retirement community, where he lives with his mother. He has had a stroke and has fallen on hard times. If there is any chance at all that he is Harry's father, but Harry and William wanted to remain brothers, Harry and William themselves would have had a DNA test and would be sending this man financial support to keep him quiet. Hewitt himself may could even blackmail the palace to help him if he were the father—but he has not.
And lastly, if Harry were not blood, once he and Megan betrayed the Royal Family, the palace could have leaked the "news" of his stray DNA to the press, making it easier to pry him out of the line of succession.
In fact, in today's world, adventurous snoops from the shameless British tabloids may have picked up a cigarette butt or a drinking glass from both parties LONG AGO and had them tested. But nothing has emerged. If the tabloids are sitting on anything, it's probably the DNA proof that Charles is the father.