People who worked on the Iron King series worked on UltraSeven from what I've read online and on this wiki. Sure, he's not as related to the Ultra series like Gridman, Izenborg, and others, but there's some Tsuburaya in him. Plus, that'd mean we'd have to delete the three/four Non-Ultra kaiju from the wiki.
But I guess it's up to the higher ups. Me? I'd let him stay, since I've seen him in so many Ultraman related images and what not, and even has mention of Ultraman on his DVD box set.