Yes, my guess is that the lawyers advised them to can the idea of a .223 in a rear locking beefed up 'rimfire' action.
These type of actions can generally handle up to .222 factory loads, as evidenced by the offerings from European manufacturers such as Anschutz and Weihrauch.
Shouldn't be a problem in converting to K Hornet.
I wouldn't though,
use it as intended !
I have a Model 40, an Anschutz 1742 .222, and a Vanguard Special Varmint in .223 .
They all complement each other.
In the Hornet, I use the lighter pills of 33gr, 35gr and 40gr as fast as I can get them to go,
and they shoot well.
40gr and 50/52 with the .222,
and 55gr with the .223 . GameKings and Nosler Ballistics.
So far, the Hornet has shot the smallest groups at 100mtrs, but I don't experiment and change loads much.
The .222 is ever reliable to produce MOA.
I have to do a bit more work with the .223, though.
I hope to get out this long weekend and shoot some 200mtr groups with them all.
cheers,
Sean in Godzone.