Dude. No.
The translated summary from Redon doesn't say "Zoro says King's attack is as fast as a laser beam". It says "Zoro hardly dodges it, he says it cannot be defended because it's like a laser beam."
Which given the wording seems more like an explanation as to why Zoro didn't attempt to block it like he did with previous attacks from King than a comment on its speed. Otherwise it would've made more sense to say something like it cannot be intercepted/countered or it cannot be evaded. It takes less speed to position your arms/swords to block an attack than to physically move out of the way of an attack after all.
There is other actually legit LS stuff for OP. This isn't it. This is a vague comparison (especially since we haven't seen the actual attack itself with no scans posted yet and it may visually give off the feel of a laser) which doesn't stand on its own. If past LS feats didn't exist this is definitely not something that would hold water and be usable as proof of LS OP, and as supporting evidence alongside other feats it's one of the worse ones and not one i'd use in a debate.