Time to whip out the big guns. Well, maybe not THE big guns, but some hopefully convincing arguments. Jose, you're my bro, but you aren't talking sense.
To start this off, I want to remind everyone that Kirby is not, by any stretch of the imagination, impervious to physical attacks. Perhaps his malleability can give him some protection, but punctures, sharp objects, and flattening are three things he is definitively vulnerable to.
Now, watch this video:
A tank. Clearly not human. Kenshiro faced down the tank, took quite a beating from it, and calmly used his amazing strength and technique to wear it away little by little until it exploded. Techniques like this are remarkably similar to getting poked a million times, and they would absolutely wear Kirby down. Of course, Kirby would also be on the attack, but even with the Rainbow Sword and Kenshiro's power, it would take a metric fuckton to wear down Kenshiro's defenses to the point of death.
Kenshiro is a master of his craft. His techniques come from training and mastery. Yes, when Kirby inhales an enemy, he knows how to use his power, but he never knows how to use it to the extent of what he is copying. His knowledge of Kenshiro's techniques would likely be limited to a few moves that would most likely be very successful...if Kenshiro doesn't wear him down first.
In a battle of Kenshiro vs. Kirbshiro, it would be a test to see who would fall first. Remember that Kenshiro simply has massive raw power independent of his knowledge of the Meridian Points, and that raw power is something Kirby is vulnerable to.
I'm not saying Kenshiro would absolutely win, but signs point to it.