Kizaru never used a sword, he only used his power and gave it the shape of a sword so he’s hardly a swordsman in my book. Also Zoro has an unresolved conflict with Fujitora too, which is way more recent than his "beef" with Kizaru.
We can hardly say Kizaru has beef with Zoro anyway, since he was fighting all the crew, not Zoro specifically. Fujitora, on the other hand, had a 1 on 1 fight with Zoro. And he’s an actual swordsman fighting with a real sword.
Also, Kizaru fighting only with his light "sword" would be too restrictive, as he can do so much more with his ability.