He can deny it, sure. But that doesn't excuse the comparisons.
Plys, Sonic Team have made some... questionable decisions with Shadows personality. Such as stating he has no friends, despite that being a blatant lie.
In his defense, he doesn't say "he has no friends" but "he’s not friends with Sonic".
Still eventough Iizuka doesn't want him to be like Vegeta, not all people in his team agree with him, including the one who sketched this (Terios). This concept might be scrapped but the idea lives on.