Zoro said that in regards to King saying that he isn't limiting himself to a single style, hence not referring to himself as a fighter of a particular style. Just like Cabaji didn't limit himself to swordsmanship but was a fire spitting acrobat (you could say Cabaji is the free version of King, using all kinds of tricks). And there is a reason Zoro said he will bite King's neck off if that's what it takes to win. Why would he say that as a swordsman? And given King was classified as a swordsman in the Databooks and said himself he enjoys sword duels, he already falls within Zoro's dream.
The fact Zoro's opponents are versatile fighters (a guy with a metal body that turns every part of his body into blades, a swordsman that has Rokushiki and is buffed by a Zoan, ...) kinda shows how Zoro has not just to surpass pure sword merchants but has to defeat everyone who uses swordsmanship in any way, shape or form.